Patterns of analgesic prescribing in a South African primary care setting

Journal of Clinical Pharmacy and Therapeutics (1997) 22, 33–37

Patterns of analgesic prescribing in a South African primarycare settingI. Truter DCom BPharm MSc

Pharmacy Department, University of Port Elizabeth, PO Box 1600, Port Elizabeth 6000, South Africa

SUMMARY

The primary aim of this study was to assesspatterns of prescribing of analgesic medications ina primary care setting in South Africa. Medicationrecords of 47 103 patients for the year 1995were retrospectively reviewed. Analgesic agentsrepresented 12·3% of the total number and 14·2%of the total cost of all the products prescribed.Analgesic products were prescribed to nearlythree times as many females as males. Mostanalgesic prescriptions were for non-opioidanalgesics (93·8%). More than half (56·8%) of allthe prescriptions for analgesics were availablewithout a prescription from a medical prac-titioner. Analgesic prescription diminished as ageincreased. The high prescribing rate of analgesicsto children younger than 10 years was a cause forconcern. Furthermore, meprobamate-containinganalgesics accounted for 12·2% of central ner-vous system drugs and 28·1% of the non-opioidanalgesics that were prescribed. This finding wasalso a cause for concern due to the dependence-producing properties of meprobamate. It was con-cluded that the pharmacist has an important roleto fulfil in the counselling of patients with respectto the use of analgesic products.

INTRODUCTION

The most common pharmacological challenge encoun-tered by the physician today is the relief of pain (1).Pain is defined by the International Association for theStudy of Pain as ‘unpleasant sensory and emotionalexperience associated with actual or potential tissuedamage or described in terms of such damage’ (2) andis symptomatic of many clinical conditions.Analgesics are the mainstay in the treatment of pain

and are one of the most frequently prescribed druggroups (3). The choice of an analgesic product is

determined by various factors, for example the con-dition or type of pain being treated, the patient’shistory, contraindications to any specific medication,and specific drug characteristics including formulation.When administered in the proper setting and usedrationally, analgesics are safe. Analgesic agents, how-ever, have covert dangers when used chronically andin higher than the recommended dosages.The primary aim of this study was to analyse the

prescribing of analgesic agents in a defined patientpopulation in a primary care setting in South Africa, toidentify prescribing trends with respect to age, genderand cost.

METHODS

Prescription data were obtained from a medical aidscheme in South Africa. The data of 47 103 patientsfor a 1-year period ending on 31 December 1995 wereanalysed retrospectively. The patient sample was con-sidered to be homogeneous, and was representative ofdifferent metropolitan areas in South Africa.The prescription data were analysed with respect to

prescribing frequency, cost, patient age and gender.No diagnoses or dosage instructions were available.The Anatomical Therapeutic Chemical (ATC)

classification system was used to classify drugs intotherapeutic categories (4), and Monthly Index ofMedical Specialities (MIMS) (5) was used to identifyall meprobamate-containing analgesics on the SouthAfrican market. All costs are indicated in SouthAfrican Rands.

RESULTS AND DISCUSSION

A total of 141 236 products were prescribed to the47 103 patients in the study, at a total cost ofR8 925 918·98.

? 1997 Blackwell Science Ltd 33

Prescribing of central nervous system drugs

Central nervous system (CNS) drugs represented12·3% of the total number and 14·2% of the total costof all the products that were prescribed. CNS drugswere prescribed to a higher percentage of females(13·6% of all the prescriptions for females were forCNS drugs) than males (only 8·5% of the prescriptionsfor males were for CNS drugs).The prescribing frequency of CNS drugs in the

different therapeutic subgroups according to gender isillustrated in Table 1. Analgesics were the mostfrequently prescribed therapeutic subgroup, represent-ing 43·5% of CNS prescriptions and 21·9% of thecost. Prescribing differences were observed betweenfemales and males (÷2=813·53; d.f.=6; P<0·0001).Analgesics were the most frequently prescribed CNSsubgroup for both females and males, but analgesicsrepresented a higher percentage of the CNS prescrip-tions for males (66·2%) than for females (38·7%). Males

were prescribed a lower percentage of psycholepticsand psychoanaleptics.

Prescribing frequency of analgesics

Analgesics were classified as opioids, other analgesicsand antipyretics, and antimigraine preparations accord-ing to the ATC classification system. The prescribingfrequency of these therapeutic subgroups for femalesand males is given in Table 2. Note that analgesicswere prescribed nearly three times more frequently tofemales than to males (5569 analgesic prescriptions forfemales and 2013 for males). This finding was to beexpected, because analgesic intake is assumed to be amore female habit (6).Prescribing differences were observed between

females and males (÷2=86·78, d.f.=2; P<0·0001). Ahigher percentage of females used opioid analgesicsand antimigraine preparations, whereas a higher per-centage of males (98·1% of all males and 92·3% of

ATCcode CNS subgroup

Frequency (%) Total

Females(n=14 392)

Males(n=3041) Number %

N01 Anaesthetics 0·03 0·03 5 0·03N02 Analgesics 38·70 66·20 7582 43·49N03 Antiepileptics 3·47 3·75 614 3·52N04 Anti-parkinson drugs 0·66 0·13 99 0·56N05 Psycholeptics 36·47 17·26 5775 33·13N06 Psychoanaleptics 20·66 12·63 3357 19·26N07 Other nervous system drugs 0·01 0·00 1 0·01

Total 100·00 100·00 17433 100·00

Table 1. Prescribing frequency ofcentral nervous system subgroups*

*÷2(6)=813·53; P<0·0001.

ATCcode Analgesic subgroup

Frequency (%) Total

Females(n=5569)

Males(n=2013) Number %

N02A Opioids 1·96 0·25 114 1·50N02B Other analgesics and antipyretics 92·26 98·06 7112 93·80N02C Antimigraine preparations 5·78 1·69 356 4·70

Total 100·00 100·00 7582 100·00

Table 2. Prescribing frequency ofanalgesic subgroups*

*÷2(2)=86·78; P<0·0001.

34 I. Truter

? 1997 Blackwell Science Ltd, Journal of Clinical Pharmacy and Therapeutics, 22, 33–37

all females) were prescribed non-opioid analgesics(classified as ‘other analgesics and antipyretics’).

Prescribing of non-opioid analgesics

The 15 most frequently prescribed non-opioidanalgesics (other analgesics and antipyretics) aregiven in Table 3. Note that the most frequentlyprescribed analgesic was a compound analgesic syrup(Stopayne> syrup; Adcock Ingram Pharmaceuticals,

SA), which accounted for 11·3% of non-opioid anal-gesic prescriptions. This syrup contained paracetamol,codeine phosphate and promethazine and was avail-able without a prescription from a medical practitioner.The second and third most frequently prescribedanalgesics were also compound analgesics (Stopayne>

capsules and Stopayne> tablets), comprising paraceta-mol, codeine phosphate, caffeine and meprobamate inslightly different dosage formulations. The three mostfrequently prescribed analgesics, all marketed under

Table 3. The 15 most frequently prescribed analgesics

Rank Analgesic FrequencyPercentageof total*

1 Paracetamol 120 mg, codeine phosphate 5 mg & promethazine 6·5 mg per 5 ml (syrup) 806 11·33

2 Paracetamol 320 mg, codeine phosphate 8 mg, caffeine 48 mg & meprobamate 150 mg(capsules)

467 6·57

3 Paracetamol 320 mg, codeine phosphate 8 mg, caffeine 32 mg & meprobamate 150 mg (tablets) 388 5·46

4 D-propoxyphene 65 mg, paracetamol 400 mg, pemoline 2·5 mg & L-glutamine 25 mg (capsules) 271 3·81

5 Paracetamol 500 mg, d-propoxyphene 50 mg, diphenhydramine 5 mg & caffeine 50 mg (tablets) 258 3·63

6 Dihydrocodeine bitartrate 12·1 mg per 5 ml (syrup) 258 3·63

7 Paracetamol 500 mg, caffeine 30 mg, codeine phosphate 10 mg & meprobamate 150 mg(tablets)

217 3·05

8 Paracetamol 120 mg per 5 ml (syrup) 207 2·91

9 Paracetamol 500 mg (tablets) 196 2·76



12 Aspirin 300 mg (effervescent tablets) 153 2·15


14 Paracetamol 400 mg, codeine phosphate 10 mg, diphenhydramine 5 mg, caffeine 50 mg &phenobarbital 8 mg (tablets)

137 1·93


*Number of times analgesic was prescribed expressed as a percentage of the total number of non-opioid analgesics prescribed.

Analgesic prescribing in a primary care setting in SA 35


the same brand name, accounted for nearly a quarter(23·4%) of all analgesic prescriptions.The 15 most frequently prescribed analgesics

accounted for 56·4% of all analgesic prescriptions. Ittherefore seems that medical practitioners showeddefinite brand preferences for non-narcotic products intheir prescribing of analgesics. This fact is even moreevident if it is taken into account that 145 differentanalgesic products were prescribed, and that 15 ofthese products accounted for more than half of allanalgesic prescriptions.Eleven of the 15 most frequently prescribed analge-

sics were combination products. This high prescribingrate of combination analgesics should be further inves-tigated, because there is evidence that prolongedexposure to polycomponent or combination analgesicsis associated with a significantly higher incidence ofanalgesic nephropathy than when simple analgesicsare similarly used (7).It is notable that 56·8% of all the analgesic prod-

ucts prescribed to this patient sample were availablewithout a prescription from a medical practitioner.These products represent 41·0% of the total cost ofanalgesics in this study.Tablets were the most popular dosage form (42·4%)

for all non-narcotic analgesic prescriptions, followedby syrups (35·2%) and capsules (18·5%).Twenty-three different analgesic products that

contained meprobamate as a constituent part wereprescribed to patients. Meprobamate-containinganalgesics accounted for 12·2% of CNS drugs and28·1% of non-opioid analgesic prescriptions. The highprescribing rate of meprobamate-containing analgesicsis a cause for concern due to their dependence-producing potential.

Age and gender analysis

The mean age of patients who were prescribed anal-gesics was 37·0 years (SD=21·8 years) (Table 4). Themean age of females was 41·7 years (SD=20·2 years)and of males 15·2 years (SD=14·9 years). The meanage of patients using non-opioid analgesics was 26·6years (SD=21·8 years), with a range of 0–95 years.Patients who were prescribed opioid analgesics andantimigraine preparations were on average much older(48·4 years and 44·8 years, respectively) than patientson non-opioid analgesics.The age and gender breakdown of patients who

were prescribed non-opioid analgesics (classified as

‘other analgesics and antipyretics’) are given in Table 5.The prescribing of analgesics decreased as the age ofpatients increased. The age of female and male patientsusing non-opioid analgesics was significantly different(÷2=1422·50; d.f.=8; P<0·0001). It is noteworthy thatnon-opioid analgesics were often prescribed to youngmale patients, and that the number of prescriptionsdecreased with increasing age. The male to femaleratio of analgesic prescriptions for patients youngerthan 10 years was 1 : 1·03. Proportionately less non-opioid analgesics were prescribed to young femalescompared to males. An increase in non-opioidanalgesic prescription was seen for females aged30–59 years.Similar results were obtained in a study on analgesic

use in the Federal Republic of Germany, where it wasfound that analgesic usage reached a peak in earlychildhood with a male to female ratio of 1·1 : 1 (6).Most of the prescription drugs in that study were alsofrequently sold over-the-counter.A high percentage of non-opioid analgesics (31·6%)

was prescribed to children younger than 10 years.

Table 4. Age and gender analysis of patients using anal-gesic drugs

Descriptivestatistics

Patientsn

Meanage(years)

SD(years)

Age range(years)

OpioidsFemale 109 49·41 17·28 1–87Male 5 26·2 14·41 11–50Total 114 48·39 17·76 1–87

Other analgesics and antipyreticsFemale 5138 32·37 21·94 0–95Male 1974 11·72 12·14 0–81Total 7112 26·64 21·78 0–95

Antimigraine preparationsFemale 322 45·77 15·16 8–77Male 34 35·85 26·02 4–62Total 356 44·82 16·71 4–77

All patientsFemale 14 392 41·66 20·15 0–95Male 3041 15·17 14·86 0–81Total 17 433 37·04 21·79 0–95

36 I. Truter


Most of these prescriptions were for syrups (90·5%)and tablets (6·5%). Only a few prescriptions were forchewable tablets (0·27%), effervescent tablets (0·49%)and drops (0·49%).

CONCLUSIONS

This study shows that analgesics were prescribed moreoften to female patients than to male patients. Nearlyone-third (31·6%) of all analgesic prescriptions werefor children under the age of 10 years. In particular,young boys received a disproportionately highnumber of analgesics (56·2% of all the analgesicprescriptions for males were for males younger than10 years). Most of these prescriptions were for syrups.The high prescribing rate of analgesics containingmeprobamate was a further cause for concern dueto the dependence-producing potential of thesecompounds.More than half (56·8%) of all the prescriptions for

analgesics were available without a prescription from amedical practitioner. Furthermore, if it is taken intoaccount that most patients also buy analgesics directlyfrom their pharmacies (over-the-counter), it can beassumed that analgesics are used freely and possiblyexcessively by patients. Because there are covertdangers associated with the chronic use of analgesics,

pharmacists have a very important role to fulfil in thecounselling of patients who are using analgesics.Moreover, because analgesics are only prescribed totreat symptoms without altering the disease process, itcan be questioned whether this high prescribing rate ofanalgesics is necessary if the underlying pathology issuccessfully being treated.Further research into the prescribing and use of

analgesics in South Africa should be conducted,especially with respect to those products that are soldwithout a prescription from a medical practitioner, bypharmacies as well as other retail businesses.

ACKNOWLEDGEMENTS

The author wishes to thank Bankmed (Cape Town,South Africa) for the data provided for the study. Theinterpretation of the results does not necessarily reflectthe opinion of Bankmed. The assistance of Miss C. S.Viljoen is also appreciated.

REFERENCES

1. Moertel CG, Ahmann DL, Taylor WF, Schwartau N.(1974) Relief of pain by oral medications: a controlledevaluation of analgesic combinations. Journal of theAmerican Medical Association, 229(1), 55–59.

2. Analgesic Guidelines Sub-Committee and VictoriaDrug Usage Advisory Committee (1992) AnalgesicGuidelines. p. 160, Victorian Medical PostgraduateFoundation Inc., Australia.

3. Ahonen R, Enlund H, Pakarinen V, Riihimäki S. (1992)A 1-year follow-up of prescribing patterns of analgesicsin primary health care. Journal of Clinical Pharmacy andTherapeutics, 17, 43–47.

4. World Health Organization (WHO) (1996) AnatomicalTherapeutic Chemical (ATC) Classification Index IncludingDefined Daily Doses (DDDs) for Plain Substances. WHOCollaborating Centre for Drug Statistics Methodology,Oslo, Norway.

5. Van Rooyen RJ, Snyman JR (eds) (1995) MIMS Medi-cal Specialities. 35(8), 29–43. Times Media Limited,Pretoria, South Africa.

6. Pommer W, Glaeske G, Molzahn M. (1986) Theanalgesic problem in the Federal Republic of Germany:analgesic consumption, frequently of analgesic nephro-pathy and regional differences. Clinical Nephrology,26(6), 273–278.

7. Gibbon CJ, Swanepoel CR (eds) (1995) South AfricanMedicines Formulary. 3rd edn, p. 491, The MedicalAssociation of South Africa Publications, Cape Town,South Africa.

Table 5. Age and gender breakdown of patients who wereprescribed non-opioid analgesics*

Agegroups(years)

Female Male All patients

n % n % n %

0–9 1138 22·15 1110 56·23 2248 31·6110–19 603 11·74 509 25·79 1112 15·6420–29 597 11·62 165 8·36 762 10·7130–39 777 15·12 96 4·86 873 12·2840–49 724 14·09 59 2·99 783 11·0150–59 667 12·98 30 1·52 697 9·8060–69 385 7·49 3 0·15 388 5·4670–79 186 3·62 1 0·05 187 2·6380–100 61 1·19 1 0·05 62 0·87

Total 5138 100·00 1974 100·00 7112 100·00

*÷2(8)=1422·50; P<0·0001.

Analgesic prescribing in a primary care setting in SA 37


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Patterns of analgesic prescribing in a South African primary care setting