Introduction to Clinical Pharmacology Chapter 11 Antiviral Drugs

Antivirals: 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

Antivirals: 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

Antivirals: Adverse Reactions Gastrointestinal reactions Nausea; vomiting; diarrhea Other reactions Headache; rash; fever; insomnia

Antivirals: 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.) 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: Interactions Probenecid: > serum levels of the antivirals Cimetidine: > serum levels of antiviral valacyclovir Ibuprofen: > serum level of antiviral devoir Imipenem/cilastatin: with ganciclovir only— increased risk of seizures Anticholinergic agents: with amantadine only— increase adverse reactions of anticholinergic agent Theophylline: with acyclovir only, increased serum level of theophylline

Antiretrovirals: Actions Retroviruses: highly active antiretroviral therapy (HAART) Protease inhibitors and reverse transcriptase inhibitors Nonnucleoside reverse transcriptase inhibitors Early inhibitors Integrase inhibitors

Antiretrovirals: Uses and Adverse Reactions Used in the treatment of HBV, 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 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: 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.) 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 Rifampin: with efavirenz, nevirapine only, decreased serum levels of antivirals

Nursing 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.) 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 Diagnosis Risk for Imbalanced Nutrition: Less Than Body Requirements Risk for Impaired Skin Integrity Risk for Injury Body Image Disturbance Acute Pain

Nursing 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: 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.) 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

Nursing Process: Implementation (cont.) 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

Nursing Process: Implementation (cont.) Monitoring and managing patient needs (cont.) 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

Nursing Process: Implementation (cont.) Monitoring and managing patient needs (cont.) Body image disturbance Spend time with patients, encouraging them to verbalize their feelings regarding any change in appearance

Nursing Process: Implementation (cont.) Monitoring and managing patient needs (cont.) 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

Nursing Process: Implementation (cont.) 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: 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

Question Is the following statement true or false? A virus is larger than a bacterium.

Answer 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.

Question Is the following statement true or false? In most situations, antivirals have major adverse reactions.

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

Question Is the following statement true or false? Antiretroviral drugs are used primarily to reduce viral load in patients with HIV.

Answer 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).