A guide to drug discovery: Protecting your inventions: the patent system

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NATURE REVIEWS | DRUG DISCOVERY VOLUME 2 | OCTOBER 2003 | 823

The foundations for the law on patents in the UnitedKingdom were laid in 1624 in the Statute of Monopolies.This provided for a monopoly to be granted in a ‘letterspatent’ (that is, an open letter) to “the first and trueinventor” of “any manner of new manufactures”. Thiscovered not only the inventor of a new idea, but also aperson who brought something new into the countryfor the first time. Even before the Statute of Monopolies,a patent system had been operating in Venice since atleast 1470. In 1788, when the Constitution of the UnitedStates of America was ratified, Article I, section 8, gavepower to the US Congress “to promote the Progress ofScience and useful Arts by securing for limited Times toAuthors and Inventors the exclusive Right to theirrespective Writings and Discoveries”. This concept ofrewarding an inventor with a time-limited exclusiveright to practice his invention survives to this day in themodern patent system.

Patents are territorial rights; that is, to obtain pro-tection for an invention in a particular country, theinventor must be granted a patent for that inventionby the Patent Office of that country. Almost all coun-tries in the world now have patent systems. The rulesof these patent systems are, however, not completelyharmonized, although the general principles are thesame. The common features of these patent systemsare that the inventor can be granted a patent for aninvention if the invention is new and not obvious, if itis clearly described in the patent and if it has at leastone practical use. As a reward for making the inven-tion and for publishing details of it, the inventor isgranted a right to prevent others from making or

using the invention in the country in question for a setperiod of time, which is usually up to twenty yearsfrom the filing date of the patent application.

In addition to discussing the key criteria that an invention must satisfy for a patent to be granted tothat invention, this article describes the practicalsteps that need to be taken to obtain a patent for thatinvention. The roles that Patent Attorneys and PatentOffices play in this process are also explained.Although the examples given in this article are gener-ally of a chemical/biochemical nature, the principlesof the patent system described here apply to all forms ofinvention, whether in the chemical, mechanical, electricalor indeed any of the other technical arts.

In any dealings with the patent system, three mainfeatures should always be kept in mind: confidentiality,time limits and costs. It is of the utmost importance thatdetails of the invention be kept secret before the applica-tion for the patent is filed.With regard to time limits, thepatent process is very structured and once the applica-tion for the patent has been filed, certain acts must becompleted within certain time frames, otherwise patentrights might be irretrievably lost. Some of these timelimits are determined by the patent rules, whereas othersare set by the Patent Offices. In some cases, these dead-lines can be extended, possibly on the payment of a fee.So, it is important for the inventor to be aware of whichdeadlines can be extended, and which cannot, in thecountries in which patent protection is sought. The thirdmain feature to keep in mind is that obtaining patents isnot a cheap endeavour, and so advantage should betaken, when possible, of options that reduce the costs or

PROTECTING YOUR INVENTIONS:THE PATENT SYSTEMPhilip M. Webber

Whether you work for a multi-national pharmaceutical company, a biotech start-up or auniversity, a knowledge of the patent system is essential for understanding how best to protectthe fruits of your research. The aim of this article is to give an overview of what a patent is, howyou might get one and the rights that a patent confers.

Frank B. Dehn & Co.,Patent and TrademarkAttorneys, 179 QueenVictoria Street, London,EC4V 4EL, UK.e-mail:[email protected]:10.1038/nrd1200

A G U I D E TO D R U G D I S C O V E R Y

PRIOR ART

All information that is availableto the public (for example, bymeans of a written or oraldescription, by use or in anyother way) before the prioritydate of the patent application.

824 | OCTOBER 2003 | VOLUME 2 www.nature.com/reviews/drugdisc

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and has been judged to have satisfied the criteria forpatentability (BOX 1), will it be granted as a patent. (Forexample, in patent applications that relate to high-throughput screening assays, Applicants often try toclaim all new drugs that might be found using suchassays. Such Claims are rarely allowed by most PatentOffices because the Claims try to cover drugs that are notadequately defined in the patent application.) Patents aregenerally made up of a number of different sections(TABLE 1), each of which is intended to satisfy a particularrequirement of the patent system.

The format of patent applications and patents is gen-erally the same around the world. The front page of apublished patent application or patent contains biblio-graphic details of the application/patent. It includes thedate that the application/patent was filed, the name ofthe Applicant for the application/patent, the name(s)of the inventor(s) and the application/patent number.The title and abstract of the patent application areincluded primarily for searching purposes; that is, to helpthe public and Patent Offices locate applications/patentsthat are of interest to them. The first page of the applica-tion itself usually starts with a paragraph which summa-rizes what the invention relates to. This is followed by adescription of the background to the invention, whichputs the invention into an appropriate context. Thencomes a description of the invention and some of thepreferred features. This is followed by some Examples ofhow the invention might be put into practice. Thereare often also some drawings or graphs at the end ofthe patent application that help to illustrate some of theExamples of the invention. The Examples are followedby the most important part of the patent application —the Claims. These define explicitly in words, chemicalformulae and/or DNA or amino-acid sequences (but notpictures, graphs or diagrams) what the Applicant isclaiming as the invention. Patent Claims have a specifi-cally defined format, some examples of which are givenin BOX 2. As can be seen, patent protection can beobtained not only for products, but also for uses,methods and processes. Products that are commonlyclaimed in the chemical/biochemical field includechemicals, proteins, genes, antibodies, vectors, cells,transgenic animals and plants; and the uses thereof.

It should be noted that the Claims in BOX 2 relate notjust to single chemical entities but to broadly definedchemical structures. In the case of the US patent thatcovered albuterol sulphate (Ventolin; GlaxoSmithKline)(BOX 2), although the main invention related to the activeingredient salbutamol, claim 1 was directed to a broadclass of 1-phenyl-2-amino ethanol derivatives so as toexclude competitors from this area. If the Claim hadbeen limited to the salbutamol molecule alone, a com-petitor might easily have been able to get around thescope of the patent merely by making a simple change toa non-essential functional group. This illustratesanother of the key points of the patent system — theClaims should try to cover not only the key examples ofthe invention that have been proven to work, but also allmodifications which have (or are likely to have) thesame technical effect.

defer the incurring of costs for as long as possible.Fortunately, there are various mechanisms for doing this,some of which are explained below.

It must be emphasized that this article merely pro-vides guidance on the general principles of the patentsystem. As mentioned above, the patent systems aroundthe world are not completely harmonized and numer-ous differences between patent systems do exist.Consequently, it is recommended that professionaladvice be sought for any specific patent-related matter.

What is a patent?A patent is a legal document that contains a descriptionof a new invention. The invention can be described withthe aid of words, tables, diagrams, chemical structures,sequences and the like, and the patent will usuallyinclude one or more worked examples to illustrate howthe invention might be put into practice. This descrip-tion is written with the person skilled in the relevant areaof technology in mind. Patents also contain an explicitwritten definition of what the Applicant is claiming tohave invented; that is, the Claims. It is these Claims thatdefine the scope of the rights that are granted to theApplicant. (Except in the United States, where patentsare applied for in the names of the inventors, patents areusually applied for in the name of a company. I shall referto this company as the ‘Applicant’.) The differencebetween a patent and a patent application is an impor-tant one. Before the patent is granted, it is called a ‘patentapplication’.Anyone can claim to have invented anythingin a patent application, but it is only after the applicationhas been examined by the appropriate Patent Office,

Table 1 | Anatomy of a patent

Subsection of the patent Function

Title and abstract Facilitates searching by the public and by Patent Offices.

Background description Assists in the understanding of the invention.

Statements of invention Basis for Claims/restrictions to Claims.

Examples/figures How to put the invention into practice; support for the Claims.

Claims Explicitly define the scope of the invention.

Box 1 | Main criteria for patentability

Novelty: the invention (as defined by the Claims) mustbe new over everything that has been made available tothe public before the priority date of the patentapplication (that is, the PRIOR ART).

Inventive step: the invention (as defined by the Claims)must not be obvious to a person skilled in the relevantarea of technology as of the priority date of the patentapplication.

Enablement: the patent application must clearlydescribe how the invention can be put into practice bya person skilled in the relevant area of technology.

Support: the breadth of the Claims must be justified by the description of the invention given in the patent application.


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there are competitors working in the same area oftechnology, the first to file a patent application to aparticular invention will generally be the one who isgranted patent rights to that invention, assuming thatthe invention satisfies the patentability criteria. (Animportant exception to the latter rule is in the UnitedStates, where the first person to invent a particular

When should you file the patent application?As the patentability of the invention will be judged onwhat was known to the public before the date of filing thepatent application, it is clearly important to obtain the earliest possible filing date and for all details of theinvention to be kept secret until the patent applicationhas been filed. Furthermore, in situations in which

Box 2 | Examples of patent claims

US 3,644,353 Ventolin (Salbutamol)1. A compound of the formula at right, in which:

• R1

represents a hydrogen atom or alkyl of 1 to 6 carbon atoms;

• R3

represents cyclopentyl, alkyl of 1 to 6 carbon atoms, or alkyl of 1 to 6 carbon atomssubstituted by morpholino, indolyl, phenyl substituted by hydroxy or methoxy, or phenoxy;

• X represents hydroxymethyl or β-hydroxyethyl, X being β-hydroxyethyl only when R1

is a hydrogen atom and R3

istert-butyl; or a physiologically acceptable acid addition salt thereof.

2. The compound of claim 1 which is a α1-tert-butylaminomethyl-4-hydroxy-m-xylene-α1,α3-diol.

EP 0951908 A2 Viagra (Sildenafil)1. The use of a compound for the manufacture of a medicament for treating sexualdysfunction in a female animal with an injured spinal cord, or in a male animal with aninjured spinal cord wherein said male animal exhibits essentially no residual erectilefunction, wherein said compound is a compound of the formula at right, wherein:

• R1 is H; C1–C

3alkyl; C

1–C

3perfluoroalkyl; or C

3–C

5cycloalkyl;

• R2 is H; C1–C

6alkyl optionally substituted with C

3–C

6cycloalkyl; C

1–C

3perfluoroalkyl; or

C3–C

5cycloalkyl;

• R3 is C1–C

6alkyl optionally substituted with C

3–C

5cycloalkyl; C

1–C

6perfluoroalkyl; C

3–C5 cycloalkyl; C

3–C5 alkenyl;

or C3–C

6alkynyl;

• R4 is C1–C

4alkyl optionally substituted with OH, NR5R6, CN, CONR5R6 or

CO2R7; C

2–C

4alkenyl optionally substituted with CN, CONR5R6 or CO

2R7; C

2–C

4

alkanoyl optionally substituted with NR5R6; (hydroxy)C2–C

4alkyl optionally

substituted with NR5R6; (C2–C

3alkoxy)C

1–C

2alkyl optionally substituted with

OH or NR5R6; CONR5R6; CO2R7; halo; NR5R6; NHSO

2NR5R6; NHSO

2R8;

SO2NR9R10; or phenyl, pyridyl, pyrimidinyl, imidazolyl, oxazolyl, thiazolyl,

thienyl or triazolyl any of which is optionally substituted with methyl; wherein R5

to R10 are…; or a pharmaceutically acceptable salt thereof.

2. A use as defined in claim 1, wherein said compound is selected from sildenafil,and pharmaceutically acceptable salts thereof, and the compound having thestructure at right; and pharmaceutically acceptable salts thereof.

X

HO CH.CH.NHR3

OH R1

R3O

R4

N

HNN

N

R2

R1O

CH2CH2O

N

O

O

N

HNN

N

CH2CH2CH3

CH3O

EP 0219225 B1 Zantac (Ranitidine)1. A process for the preparation of ranitidine, having the formula

or an acid addition salt thereof, characterized in reacting N-[2-[[[5-(hydroxymethyl)-2-furanyl]methyl]thio]ethyl]-N ′-methyl-2-nitro-1,1-ethenediamine having the formula

in an organic solvent with dimethylamine and an N,N-(dimethylamino)triphenylphosphonium halidehaving the formula

wherein Hal denotes bromo or chloro, after which the ranitidine thereby formed if desired is convertedinto an acid addition salt thereof.

O(CH3)2NCH2 CH2SCH2CH2NHCNHCH3

CHNO2

OHOCH2 CH2SCH2CH2NHCNHCH3

CHNO2

(C6H5)3PNMe2, Hal–+


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used to define a generic formula that encompasses themost promising leads (see the generic formulae given inBOX 2). These data can be included in the patent applica-tion as examples of how the invention can be put intopractice. It can also be used to try to prove to the PatentOffice Examiners in due course that the breadth of theClaims is justified.

Filing the priority applicationThe first patent application that is filed will generally bea ‘priority application’, and the filing date of that appli-cation will be called the ‘priority date’. Under an inter-national agreement called the Paris Convention, themajority of countries will allow patent applications thatrelate to the same invention as the priority applicationto be filed in their countries within an inextensibleperiod of one year from the priority date (that is, the‘priority year’); furthermore, those latter applicationswill be treated as if they were filed on the priority date.The importance of obtaining an early priority date isthat the novelty and inventive step of an invention willbe judged (during the examination of the patentapplication) only on what was known to the publicbefore the priority date of the patent application.Consequently, any public disclosures of the invention,as defined in the priority application made by theApplicant during the priority year, will be disregardedduring the examination of the patent application.(There are, however, important exceptions to this gen-eral principle and so it is prudent not to disclose detailsof the invention before any corresponding patentapplications are filed at the end of the priority year.)

The end of the priority year is generally an expen-sive time for the Applicant, because any foreign patentapplications that the Applicant wishes to file on thebasis of the priority application will have to be filed atthat time. For each foreign patent application that isfiled, official Patent Office fees, Patent Attorney’s feesand translation costs (if the text of the patent applica-tion has to be translated into a foreign language) willusually have to be met (see later discussion of costs).For this reason, virtually all Applicants make use of thepriority system, because it confers a number of dis-tinct advantages: it avoids the need for an Applicant tofile patent applications in all desired countries at thesame time; it gives the Applicant one year to developtheir invention further and to decide whether it isworthwhile from a commercial perspective to seekpatent protection; and it also provides additional timeto seek financial backing. It is also possible in somecountries (for example, the United Kingdom) toobtain a Search and an Examination Report on a pri-ority application within the priority year. Armed withsuch Reports, the Applicant will then have a reason-able indication as to whether corresponding patentapplications are likely to be granted in other countries,before incurring the costs of filing those foreignpatent applications. One or more further priorityapplications can be filed in the priority year that con-tain more information about the invention; for example,details of further experiments.

invention can be granted rights to that invention insteadof the person who filed the first patent application tothat invention.) However, the danger of filing too earlyis that the chemical space around the initial leads mightnot have been adequately explored, and so consequentlythe Claims might be drafted too narrowly. This mightleave holes in the patent protection, which could poten-tially be exploited by competitors. Alternatively, if theClaims are drafted too broadly, then they might encom-pass compounds that do not possess the claimed activity.This could lead to the refusal of the patent application ifthe scope of the Claims could not validly be limited toexclude non-efficacious compounds.

Ideally, before the patent application is filed, theApplicant should have in their possession data from oneor more experiments that give an indication of howbroadly the invention should be claimed; for example,some structure–activity-relationship data that can be

Months

File priority application.

File International application.Pay filing and search fees.

Receive International SearchReport from examiner.

Publication of International applicationand International Search Report.

Pay International PreliminaryExamination fee (optional).

Receive International PreliminaryExamination Report (optional).

File national/regional applications basedon international application (FIG. 2).

0

12

~16

~18

19

~25–28

30/31

Figure 1 | International application. This figure shows themain steps in the filing and examination of an Internationalpatent application and the time scales involved. At the end ofthe 30/31-month period, the International patent applicationis not granted; one or more regional/national patentapplications must then be filed if the Applicant wishes toobtain granted patents.


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The examination processAfter the patent application has been filed and theappropriate fees have been paid, it will be assigned to aPatent Office Examiner who is familiar with the tech-nology described in the application. It is the job of thePatent Office Examiner to determine whether or notthe patent application satisfies the criteria for the grantof a patent. The examination process generally consists oftwo parts: search and substantive examination.

The Search Report. The Examiner will carry out a searchto see whether any matter that falls within the scopeof the Claims was publicly known before the priority

Filing further patent applicationsAt the end of the priority year, the text of the final patentapplication has to be resolved. This will usually containall of the information contained in all of the priorityapplications. After this time, no more information canbe added to this final patent application. The aim is toensure that this final text complies with all of the criteriafor patentability (BOX 1).

The Applicant must now come to a decision as towhere protection for the invention is to be sought. Thereare a number of options: to file an International applica-tion; to file a regional application (which covers morethan one country); to file one or more national (that is,single country) applications; or any combination of theabove. These options are illustrated in FIGS 1 and 2.

International patent applications. A popular option isto file an International application. Under the PatentCooperation Treaty (PCT), a single patent applicationcan ‘designate’ one or more of the 122 countries whichare, at present, signatories to the PCT. Using thisroute, an International Search Report (ISR), and, ifdesired, an International Preliminary ExaminationReport (IPER), can be obtained on the invention.However, once the Applicant has received the ISR andIPER, this is the end of the ‘International phase’ of thePCT application. No PCT patents are actually granted— there is no such thing as an International patent! Ifthe Applicant wants to obtain the grant of any patentrights, they must then file one or more nationaland/or regional patent applications, which are basedon the International application. There are, however,two key advantages of the PCT system. The first isthat, after receiving the ISR and IPER, the Applicantwill have a better indication of whether or not anypatents are likely to be granted before incurring thecosts of filing numerous national and/or regionalpatent applications. If the ISR and IPER are very nega-tive, then all patent applications can be abandoned atthat time. The second advantage is that, by using thePCT route, the deadline for filing national and/orregional patent applications is deferred until approxi-mately 30 months after the earliest priority date. So,the Applicant should have a better idea at that time of thecommercial value of the invention and in particularwhether or not its value justifies the expense of filingfurther patent applications.

Regional applications. There are a small number ofregional agreements under which a single patent appli-cation can cover a number of geographically relatedcountries. The most important of these is the EuropeanPatent Convention (EPC), the members of which arelisted in BOX 3. Under the EPC, a single patent applica-tion can be searched and examined by an Examinerfrom the European Patent Office (EPO). If the neces-sary criteria for patentability are met, then a Europeanpatent will be granted. This European patent can thenbe converted into a bundle of individual-countrypatents so as to provide protection for the invention inone or more of the 27 member states of the EPC.

Months

File priority application.

File national/regional applications.Pay filing and search fees.

Receive Search Report from examiner.

Publication of applicationand Search Report.

Pay examination fees.

Receive Substantive ExaminationReport from examiner.

File response to SubstantiveExamination Report.

Examiner considers response.

Grantof application.

Refusalof application.

0

12

~15–17

~18

~24

~36–60

~42–66

~48–72

~60–84

Figure 2 | National/regional application. This figure shows anexample of the main steps in the filing, examination and grantof a national/regional application (on the basis of a Europeanregional application).


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Offices are generally not exhaustive and it is possiblethat significant prior art documents might not be found.

As can be seen from FIG. 3, the Search Report isessentially a list of documents that the Examiner con-siders relevant to the patentability of one or more ofthe Claims of the patent application. It will then be upto the Applicant, with the assistance of a PatentAttorney (BOX 4), to review the contents of the citeddocuments. If it is decided that all of the key featuresof the invention were known before the priority date ofthe application, and that there is therefore little likeli-hood of obtaining any patent protection, the applica-tion might simply be abandoned (and no further costsincurred). Alternatively, if the prospect of obtainingvaluable patent protection remains, then the Substan-tive Examination fee will need to be paid. The appli-cation is usually published with the Search Report atthis time (which is generally about 18 months after thepriority date).

Substantive examination. On payment of the Sub-stantive Examination fee, the Examiner will give detailedconsideration to the documents that were cited in theSearch Report. These are read in depth by the Examinerwith a view to establishing precisely which aspects of theinvention — as claimed in the Claims — are, in the opinion of the Examiner, novel and inventive. TheExaminer will also consider whether the patent applica-tion satisfies the other criteria for patentability; that is,that the Claims are clear and concise, that the breadth ofthe Claims is supported by the description and that thedescription provides details of how the invention can beput into practice. If one or more of the patentabilitycriteria are not met, the Examiner will issue anExamination Report (variously known in the patentprofession as an ‘Official Action’, ‘Office Action’ or‘Official Letter’), which provides details of any objec-tions to the patent application. A deadline for the filingof a response will also be set. These deadlines varyfrom country to country, but they are usually betweentwo and six months. Extensions of time are also avail-able in some (but not all) countries; most extensionsincur a fee. If a response is not filed within the pre-scribed period, then the application might be rejected.An example of an extract from such a Report is shownin BOX 5.

An important role of the Patent Attorney is toconsider the merits of the objections raised by the Examiner and to advise the client on how to maxi-mize protection for the invention in the light of theExaminer’s objections. The Patent Attorney might con-sider that some of the objections are unfounded, and soarguments against those objections might be filed. Inother cases, the scope of what is being claimed mighthave to be limited so as to exclude what was alreadypublicly known before the priority date. Furthermore,some of the words of the Claims might have to bechanged in order to ensure that the Claims are clear.

Once a response has been filed by the Applicant(usually through a Patent Attorney), the Examiner willreassess the patentability of the invention in light of the

date of the invention. To carry out this search, theExaminer usually uses databases of earlier patents andpatent applications (or abstracts of patent applica-tions; for example, Japanese patent abstracts) and alsoscientific databases (such as Chemical Abstracts andBIOSIS). As mentioned previously, for the Claims tobe patentable, they must generally be novel and inven-tive over everything that was publicly known beforethe priority date of the patent, irrespective of the lan-guage and the age of the document. The results ofsuch a search will then be sent to the Applicant in theform of a Search Report. Copies of the cited docu-ments are also usually provided. An example of anextract from a Search Report is shown in FIG. 3. Itshould be noted that searches performed by Patent

Box 3 | Members of the European Patent Convention

Austria; Belgium; Bulgaria; Cyprus; Czech Republic; Denmark; Estonia; Finland; France;Germany; Great Britain; Greece; Hungary; Ireland; Italy; Luxembourg; Monaco;Netherlands; Portugal; Romania; Slovakia; Slovenia; Spain; Sweden; Switzerland/Liechtenstein; Turkey.

SEARCH REPORT

Electronic database consulted during the search:

BIOSIS, WPI data, PAJ, MEDLINE, CHEM ABS Data, EMBASE

C. DOCUMENTS CONSIDERED TO BE RELEVANT

NASLUND et al: "Distal small bowelhormones"DIGESTIVE DISEASES AND SCIENCESvol. 43, no.5, May 1998 (1998-05),pages 945-952; especially page 946,column 1, second paragraph

PCT application WO 98 39022 A(1149336 ONTARIO INC)11 September 1998 (1998-09-11)The whole document(see especially claim 1)

1–5, 7, 9

1–23

Category

X

Y

Citation of document, with indication, where appropriate, of therelevant passages

Relevant to claim no.

Document of particular relevance, the claimed invention cannot be considered novel or cannot beconsidered to involve an inventive step when the document is taken alone.Document of particular relevance, the claimed invention cannot be considered to involve an inventivestep when the document is combined with one or more other such documents, such combinationbeing obvious to a person skilled in the art

X

Y

Figure 3 | An example of a Search Report.


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addition, Applicants for US patents have an obligationto provide the US Patent and Trademark Office(USPTO) with details of all documents and acts, such asprior sales, which the Applicant considers to be materialto the patentability of the Claims. So, in some countries,patents are more easy to obtain than in others.

Rights conferred by a granted patentOn the grant of a patent (but not before), the Applicantis given rights to prevent others from exploiting theirinvention. These rights differ from country to country,but can be exemplified by the rights given to US patentowners: in the United States, the patent grants “the rightto exclude others from making, using, offering for sale,or selling the invention throughout the United States orimporting the invention into the United States”. If theinvention relates to a process, similar rights apply toproducts made by the patented process.

So, the grant of a patent is a negative right — theApplicant has the right to stop others from exploitingthe patented invention for a set time (that is, while thepatent is in force) within a certain geographical area(that is, in the country in which the patent wasgranted). The grant of a patent provides the Applicantwith no right to exploit their invention. Often, otherlaws (for example, health and safety laws) will have tobe complied with before the Applicant can practicethe invention. In most cases, if the Applicant wishes toenforce their patent rights against an infringer, theywill have to issue proceedings in the courts againstthat infringer. If the Applicant wins, then the usualremedy is an injunction against the infringer to pre-vent further infringement of the patent, and theaward of monetary damages.

If the Applicant does not wish to exploit theirpatented invention, they might choose to license theinvention to one or more parties in return for licencefees. In other cases, the value of the patent lies in its abil-ity to act as a bargaining tool in negotiations with com-petitors; for example, to try to secure a licence underone of their patents.

The duration of the patent right is now harmonizedin most countries as being 20 years from the filing dateof the patent (although some countries allow longerterms for patented medicines). However, to keep thepatent in force, most Patent Offices require the paymentof annual renewal fees. Once the patent is no longer inforce, the public is free to use the invention, although itshould be kept in mind that other Applicants mighthave patented improvements/variations of the inventionin the meantime.

Is the patent valid?Even though an Applicant might have been granted apatent in a particular country, the validity of the patentcan still be challenged. As mentioned above, in somecountries the examination procedure is not very rigor-ous; in others there is essentially no pre-grant exami-nation system. In most countries, however, there aremechanisms by which the public can challenge thevalidity of a patent, either directly at the Patent Office

arguments and/or amendments filed by the Applicant.If the application is found to be acceptable, it is thengranted. If not, one or more further rounds of examina-tion report/response might be necessary. If, however, noreal progress is being made towards the grant of thepatent, then the patent application might be rejected.The patent systems of most countries allow for appealsto be filed against such rejections, although such appealsare generally costly procedures.

Although the majority of countries have patent sys-tems that are based on the above principles, there arenumerous exceptions. For example, South Africanpatents are not examined at all; they are merely granteddirectly after they are filed. New Zealand patents areexamined for novelty but not for inventive step. In theUnited States, the results of the Examiner’s search areincluded within the Substantive Examination Reports;they are not issued as separate Search Reports. In

Box 4 | The role of Patent Attorneys in the patenting process

The role of Patent Attorneys (known as Patent Agents in some countries) is to assisttheir clients in obtaining effective protection for their inventions and to advise themon the intellectual property rights of others. So, the Patent Attorney will generally beinvolved in writing the initial patent application and filing it at the Patent Office.During the examination of the patent application, the Patent Attorney will assisttheir clients in overcoming any objections that are raised to their patent applicationsby the Patent Office Examiners, with the aim of securing the broadest validprotection for the clients’ inventions.

Patent Attorneys are generally graduate — often postgraduate — scientists whoare legally qualified in patent law. Some work in patent departments of industrialorganizations, others work in private firms that are often organized in a similarmanner to that of solicitors. The key point to note, however, is that Patent Attorneysare independent of the Patent Offices. They also have an obligation to clients to keepdetails of their inventions confidential.

Most Patent Attorneys specialize in a particular area, such as mechanical, electrical,chemical or biochemical inventions and so, when selecting a Patent Attorney (or a firmof Attorneys) to use, it is clearly important to ensure that they have expertise in yourchosen area. (Most patent firms have websites from which information can be obtainedon the background of each of their Patent Attorneys). So, a good Patent Attorneyshould have the appropriate scientific knowledge to understand the background to theApplicant’s invention, have experience in drafting patent applications to suchinventions, be familiar with objections that are often raised by Patent Offices to suchinventions and be familiar with how to overcome such objections (or, better still, knowhow to avoid them in the first place).

Box 5 | An example of an extract from an Examination Report

Claim 1 is directed to the use of guanidine derivatives for the treatment of rheumatoidarthritis. US patent application no. 4,453,776 discloses the use of tetramethyl-2-phenylguanidine for the treatment of rheumatoid arthritis. Thus claim 1 lacks noveltyunder Article 54(2) EPC [European Patent Convention].

Claim 6 is directed specifically to the use of 1,1,3-trimethyl guanidine for thetreatment of rheumatoid arthritis. Landsdowne et al. (1993) discloses the use of1,1,2-trimethyl guanidine as an anti-inflammatory analgesic. The use of such ananalgesic for the treatment of rheumatoid arthritis would have been obvious to aperson skilled in the art. Thus claim 6 lacks inventive step under Article 56 EPC.

The term ‘derivatives’ in claim 1 has no standard meaning in the art. Hence claim 1lacks clarity under Article 84 EPC.

The applicant is requested to file new claims which take account of the abovecomments within a time period of 4 months from the date of this letter.


R E V I E W S

cost £3,000–4,000, with a further £500–1,000 addedonce the International Search Report has been issued.If the Applicant wishes to file corresponding patentapplications in Europe and the United States only, thecosts are likely to be around £4,000–5,000; for a longerlist of countries, the costs will be proportionatelygreater, particularly if translations of the applicationare required. For the examination of a pair ofEuropean and US applications, perhaps £5,000 wouldbe required. On the grant of a European patent appli-cation, translations of the granted application willneed to be filed in each of the chosen EPC memberstates — this can cost up £20,000. So, over a period ofabout four-and-a-half years after the initial patentapplication has been filed, £40,000 might have beenspent on securing patent protection in a selection ofEuropean countries and in the United States. To pro-ceed with applications in a selection of other countries,perhaps a further £20,000 would be required. Withannual renewal fees also included, the total expendi-ture over a six-to-seven year period might rise toaround £75,000. It should be remembered, however,that the patent applications can be abandoned at anypoint during the examination process or after grant.

ConclusionsThe main goal of the patent system is to promote inno-vation and to give Applicants an incentive to developand market products that will be of benefit to society.The fact that the majority of countries around the worldoperate patent systems is evidence of their recognitionthat this system is achieving this goal. The patent systemis of course vital to the pharmaceutical industry to allowit to recoup the vast expenses that are incurred duringthe research and development phases of a new drug.

AcknowledgementsThe author would like to thank the Patent Attorneys of Frank B. Dehn & Co. fortheir useful comments during the preparation of this article.

Online links

DATABASES OF PATENT APPLICATIONS AND PATENTSEuropean patent database: http://gb.espacenet.com/US Patent Office database:http://www.uspto.gov/patft/index.htmlVentolin patent:http://www.patentfetcher.com/PatentPDFs/Pats/US/36/44/US3644353.pdfViagra use patent application:http://l2.espacenet.com/espacenet/viewer?PN=EP0951908Zantac process patent:http://l2.espacenet.com/espacenet/viewer?PN=EP0219225

FURTHER INFORMATIONEuropean Patent Office website: http://www.european-patent-office.org/Patents in general | how to obtain a European patentCountries for which international patent applications can be designated: http://www.wipo.int/treaties/documents/english/pdf/m-pct.pdfUS Patent and Trademark Office website: http://www.uspto.govHow to get a patentUK Patent Office website:http://www.patent.gov.ukWhat is a patent? | how to apply for a patent | international and national patentorganizationsAccess to this interactive links box is free online.

or in the courts. In particular, if an Applicant tries tosue a competitor for infringing their patent, then thecompetitor will often try to show that the patent isinvalid; that is, that the patent does not satisfy the maincriteria for patentability (BOX 1) and should not havebeen granted in the first place. In most cases, a competi-tor working in the same field as the Applicant will bemuch more familiar with the preponderance of docu-ments that were published before the priority date of thepatent (that is, the prior art) than a Patent OfficeExaminer, and so such competitors often manage toinvalidate granted patents by identifying additionalprior art. If the Claims are found to be invalid duringinfringement proceedings then, unless the Applicant canamend them to restore their validity (for example, byrestricting the scope of the Claims), the patent will berevoked. The Applicant will then lose all rights in thepatent. However, in the United States, amendment ofthe patent during infringement proceedings is not avail-able; the Applicant must return to the USPTO to havethe patent re-examined and re-granted with amendedclaims. Consequently, although suing a competitor forpatent infringement brings with it the prospect of finan-cial reward (in terms of damages), there will often alsobe a risk that the Applicant’s patent will be revoked.

The costs of obtaining patent protectionAlthough the costs involved in obtaining patent protec-tion for a new drug might be relatively insignificant to alarge pharmaceutical company in comparison with theoverall costs of bringing a new drug to market, for aprivate inventor the costs involved should not be under-estimated. As will be appreciated from the above, PatentOffice Examiners and Patent Attorneys are required tohave a unique combination of scientific, legal andlanguage skills and so the official Patent Office feesand Attorney fees have to reflect the training and skillsthat they have in this regard. Although the Patent Officesgenerally have fixed fees (which vary from country tocountry) for the filing, search, examination and grant ofpatents, Patent Attorneys usually charge fees on the basisof the time spent working on a particular case.

So, the charges made by a Patent Attorney will bedependent on a number of factors, including the com-plexity of the invention; the number and length of thedocuments to be considered in the Search Report; andthe number and complexity of the objections raisedby the Examiners in the Substantive ExaminationReports. It is simply impossible, therefore, to state inadvance with any accuracy how much a patent is likelyto cost to obtain. The following cost estimates shouldtherefore be viewed with these points in mind.

A typical UK pharmaceutical patent applicationcan cost £3,000–6,000 to draft and file as a priorityapplication. If an International patent application isfiled on the basis of the priority application, this can

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A guide to drug discovery: Protecting your inventions: the patent system