Chapter 45

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 45Drugs Treating Viral Infections

Chapter 45Drugs Treating Viral Infections


QuestionQuestion

• The transcription phase of viral replication involves the change of RNA to DNA.

– A. True

– B. False


RationaleRationale

• The transcription phase of viral replication involves the change of RNA to DNA.

– A. True

– Transcription involves the change of ribonucleic acid (RNA) to deoxyribonucleic acid (DNA).


Physiology of Viral Reproduction Physiology of Viral Reproduction • The reproduction of viruses in humans requires five steps

– Adsorption- adheres to a cell’s surface

– Penetration – entering the cell wall

– Uncoating- shedding its protein cover and allowing RNA to be replicated

– Replication- ability to reproduce

– Transcription- the change of RNA to DNA

– Synthesis – of new viral proteins

– Assembly –of new viral proteins into new viruses

– Release – of new viruses


Viral Reproduction-Antiviral drugs interfere with the various stages of replicationViral Reproduction-Antiviral drugs interfere with the various stages of replication


Selected Viral Infections Selected Viral Infections • Cytomegalovirus is a type of herpesvirus common in 80% of

people

• Hepatitis A,B & C. symptoms include jaundice, fatigue, abdominal pain, nausea, and anorexia.

• Herpes simplex is characterized by the formation of painful vesicles.

HSV 1 – lips or HSV 2- genital area

• Herpes zoster is an acute unilateral and segmental inflammation of the dorsal root ganglia caused by infection with the herpesvirus varicella zoster ( which also causes chicken pox.

• Influenza attacks both the upper & lower respiratory tracts.

• Respiratory syncytial virus

– Dangerous in children < 1 year

– Adults and children will have S & S of a cold and a cough


QuestionQuestion

• Hepatitis A is spread through blood and body fluids that contain blood.

– A. True

– B. False


RationaleRationale

• Hepatitis A is spread through blood and body fluids that contain blood.

– B. False

– Hepatitis A is spread by the oral and fecal route, not through blood or body fluids that contain blood.


Purine Nucleoside Analogue Drugs Purine Nucleoside Analogue Drugs

• The largest group of antiviral drugs are the purine nucleoside analogue drugs.

• They have selective toxicity to viruses because viral DNA polymerases are more sensitive than human polymerases to these drugs.

• Prototype drug: acyclovir (Zovirax).


Acyclovir: Core Drug Knowledge Acyclovir: Core Drug Knowledge • Pharmacotherapeutics

– Treatment of herpesviruses: HSV, herpes zoster, Epstein Barr, and CMV.

– NOT active against HIV

• Pharmacokinetics

– Administered: topical, oral, or IV.

Pharmacodynamics – effective against only ACTIVELY replicating viruses.

– Undergoes phosphorylation. In an infected cell, it is converted by the viral enzyme and incoporated into the viral cell

– Once incorporated into the virus, it terminates DNA synthesis in the viral cells


Acyclovir: Core Drug Knowledge (cont.)Acyclovir: Core Drug Knowledge (cont.)• Contraindications and precautions

– Use caution in patients with ganciclovir hypersensitivity

– Pregnancy Category C : concentration in breast milk

• Adverse effects

– Lightheadedness, anorexia, nausea, vomiting, abdominal pain, and headache

– IV form is nephrotoxic ; 70% of the drug is excreted unchanged. Distributes to the kidneys with some crystallization of the drug here

• Drug interactions

– Valproic acid, hydantoins, theophyllines, and probenecid


Acyclovir: Core Patient Variables Acyclovir: Core Patient Variables

• Health status

– Assess medical history and function of kidneys.

• Life span and gender

– Pregnancy category C.

• Lifestyle, diet, and habits

– Can transmit disease to others.

• Environment

– Assess environment where drug will be given.


Acyclovir: Nursing Diagnoses and Outcomes Acyclovir: Nursing Diagnoses and Outcomes

• Disturbed Thought Processes related to drug-induced confusion, hallucinations, or seizures

– Desired outcome: the patient will be free of thought aberrations related to drug therapy.

• Acute Pain related to drug-induced headache

– Desired outcome: drug-related pain will subside after administration of acetaminophen.

• Excess Fluid Volume related to adverse effects of drug therapy, such as nephrotoxicity

– Desired outcome: the patient will have an adequate fluid intake and output profile.


Acyclovir: Planning & InterventionsAcyclovir: Planning & Interventions

• Maximizing therapeutic effects

– Administer acyclovir tablets or capsules with a full glass of water, with or without food.

• Minimizing adverse effects

– Advise the patient to drink at least eight 8-oz glasses of water a day.

– Administer IV acyclovir over 60 minutes.


Acyclovir: Teaching, Assessment & EvaluationsAcyclovir: Teaching, Assessment & Evaluations

• Patient and family education

– Advise patients to notify the prescriber if they are pregnant or breast-feeding.

– Emphasize that acyclovir does not prevent the transmission of infection to another person and does not cure the infection ( virus may be latent)

• Ongoing assessment and evaluation

– Monitor for the effectiveness of therapy, making sure to document new lesions and assess for possible secondary bacterial infections.


QuestionQuestion

• IV acyclovir is associated with which adverse reaction(s)?

– A. Hepatotoxicity

– B. Hallucinations

– C. Nephrotoxicity

– D. Seizures

– E. B & D


RationaleRationale

• IV acyclovir is associated with which adverse reaction(s)?

– C. Nephrotoxicity

– Acyclovir nephrotoxicity appears to result from crystallization of the drug in the nephron, which can lead to renal tubular obstruction.


Drugs Used for Influenza Drugs Used for Influenza

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