copyright © 2014 wolters kluwer health | lippincott williams & wilkins introduction to clinical...

Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins

Introduction to Clinical Pharmacology

Chapter 11Antiviral Drugs

Introduction to Clinical Pharmacology

Chapter 11Antiviral Drugs


Antivirals: ActionsAntivirals: Actions

• Combat viral infections

• Interfere with the virus’s ability to reproduce in a cell

• Can be toxic to human cells

• Are more difficult to develop

– Herbal Alert: Lemon balm


Antivirals: UsesAntivirals: Uses• Labeled uses: CMV in transplant patients;

HSV-1 and -2 (genital) and herpes zoster; HIV; influenza A and B; RSV; hepatitis B and C

• Unlabeled uses: CMV and HSV infections after transplantation procedures and varicella pneumonia; CMV retinitis in immunocompromised patients; ribavirin for influenza A and B; herpes genitalis; measles


Antivirals: Adverse ReactionsAntivirals: Adverse Reactions

• Gastrointestinal reactions

– Nausea; vomiting; diarrhea

• Other reactions

– Headache; rash; fever; insomnia


Antivirals: Contraindications and PrecautionsAntivirals: Contraindications and Precautions

• Contraindicated in patients with a history of allergies

• Cidofovir (Vistide) contraindicated for patients with renal impairment and with medications that are nephrotoxic, such as aminoglycosides

• Ribavirin contraindicated for patients with unstable cardiac disease


Antivirals: Contraindications and Precautions (cont.)Antivirals: Contraindications and Precautions (cont.)

• Use during pregnancy and lactation only when the benefit outweighs the risk to the fetus or child

• Used cautiously in patients with:

– Renal impairment; low blood cell counts; history of epilepsy; history of respiratory disease


Antivirals: InteractionsAntivirals: Interactions• Probenecid: Increased serum levels of the

antivirals

• Cimetidine: Increased serum levels of antiviral valacyclovir

• Ibuprofen: Increased serum level of antiviral devoir

• Imipenem/cilastatin: With ganciclovir only—increased risk of seizures

• Anticholinergic agents: With amantadine only— increased adverse reactions of anticholinergic agent


Antiretrovirals: ActionsAntiretrovirals: Actions

• Retroviruses: Highly active antiretroviral therapy (HAART)

– Protease inhibitors

– Reverse transcriptase inhibitors

– Attachment and fusion inhibitors


Antiretrovirals: Uses and Adverse ReactionsAntiretrovirals: Uses and Adverse Reactions

• Used in the treatment of HIV and AIDS

• Adverse reactions:

– Gastrointestinal reactions: Nausea; vomiting; diarrhea; altered taste

• Other reactions: Headache; fever; chills; rash; numbness and tingling in the circumoral area (around the mouth) or peripherally or both


Antiretrovirals: Contraindications and PrecautionsAntiretrovirals: Contraindications and Precautions• Contraindicated in patients:

– With a history of allergies to the drug; during lactation

– Who are taking cisapride, pimozide, triazolam, midazolam, or an ergot derivative

• Used cautiously in patients:

– With diabetes mellitus; impaired hepatic function; pregnancy; hemophilia


Antiretrovirals: InteractionsAntiretrovirals: Interactions

• Antifungals: Increased serum level of the antiretroviral

• Clarithromycin: Increased serum level of both drugs

• Sildenafil: Increased adverse reactions of sildenafil

• Opioid analgesics: Risk of toxicity with ritonavir


Antiretrovirals: Interactions (cont.)Antiretrovirals: Interactions (cont.)

• Anticoagulant, anticonvulsant, antiparasitic agents: Decreased effectiveness when taking ritonavir

• Interleukins: Risk of antiretroviral toxicity

• Fentanyl: Increased serum level of fentanyl

• Oral contraceptives: Decreased effectiveness of the birth control agent


Nursing Process: AssessmentNursing Process: Assessment• Preadministration assessment:

– Determine the patient’s general state of health and resistance to infection

– Record vital signs, symptoms, and complaints

– Additional assessments may be necessary in certain types of viral infections


Nursing Process: Assessment (cont.)Nursing Process: Assessment (cont.)

• Ongoing assessment:

– Monitor for and report any adverse reactions from the antiviral drug

– Inspect the IV site several times a day for redness, inflammation, or pain and report any signs of phlebitis


Nursing Process: Nursing DiagnosisNursing Process: Nursing Diagnosis

• Risk for Imbalanced Nutrition: Less Than Body Requirements

• Risk for Impaired Skin Integrity

• Risk for Injury

• Body Image Disturbance

• Acute Pain


Nursing Process: PlanningNursing Process: Planning

• The expected outcome includes an optimal response to therapy:

– Management of adverse drug reactions

– Understanding of and compliance with the prescribed treatment regimen


Nursing Process: ImplementationNursing Process: Implementation

• Promoting an optimal response therapy:

– Allow the patient and family members time to talk and ask questions

– Amantadine: Observe the patient for adverse effects

– Ribavirin: Discard and replace the solution in the SPAG-2 aerosol generator every 24 hours; monitor respiratory function closely throughout therapy; is a pregnancy category X drug


Nursing Process: Implementation (cont.)Nursing Process: Implementation (cont.)

• Monitoring and managing patient needs:

– Nutritional imbalance

•Help reduce effects of nausea; keep the atmosphere clean and free of odors; provide good oral care before and after meals; notify if nausea is severe



• Monitoring and managing patient needs (cont.):

– Impaired skin integrity

•Monitor any skin lesions carefully for worsening or improvement; notify

•If administering by the IV route: Closely observe the injection site for signs of phlebitis; monitor vital signs




– Risk for injury

•Monitor acutely ill patients carefully; place call lights in a convenient place for the patient; plan activities so as to provide adequate rest periods; watch for signs of peripheral neuropathy




– Body image disturbance

•Spend time with patients, encouraging them to verbalize their feelings regarding any change in appearance




– Acute pain

•Assess patients for pain when performing routine vital signs check; explore any pain for location and intensity

•Herbal Alert: St. John’s wort



• Educating the patient and family

– Explain the dosage regimen and advise to take the drug as prescribed only

– Educate the patient of potential adverse reactions, and explain the necessity of contacting the primary health care provider immediately if symptoms for adverse reactions occur

– Develop an appropriate teaching plan


Nursing Process: EvaluationNursing Process: Evaluation

• The therapeutic effect is achieved; symptoms of the disease process subside or diminish

• Adverse reactions are identified, reported, and managed

• Patient and family demonstrate understanding of the drug regimen

• Patient verbalizes the importance of complying with the prescribed therapeutic regimen


QuestionQuestion

• Is the following statement true or false?

• A virus is larger than a bacterium.


AnswerAnswer

• False

• A virus is smaller than a bacterium. To reproduce, the virus needs cellular material of another living cell. Viral infections range from the common cold to chronic systemic infections of the liver or immune system.


QuestionQuestion


• In most situations, antivirals have major adverse reactions.


AnswerAnswer

• False

• In most situations, antivirals have minor adverse reactions such as gastrointestinal disturbances or flu-like symptoms.


QuestionQuestion


• Antiretroviral drugs are used primarily to reduce viral load in patients with HIV.


AnswerAnswer

• True

• Antiretroviral drugs are used primarily to reduce viral load in patients with HIV. Multiple drugs are used to attack the virus at different parts of the life cycle; this is termed highly active antiretroviral therapy (HAART).

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