Introduction to Clinical Pharmacology Chapter 11 Antiviral Drugs

1. Introduction to Clinical PharmacologyChapter 11Antiviral Drugs

2. 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

3. 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

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

5. 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

6. 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

7. 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

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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

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

26. 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.

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

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

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

30. 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).