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Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Introduction to Clinical Pharmacology
Chapter 11Antiviral Drugs
Introduction to Clinical Pharmacology
Chapter 11Antiviral Drugs
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
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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
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Antivirals: Adverse ReactionsAntivirals: Adverse Reactions
• Gastrointestinal reactions
– Nausea; vomiting; diarrhea
• Other reactions
– Headache; rash; fever; insomnia
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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
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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
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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
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Antiretrovirals: ActionsAntiretrovirals: Actions
• Retroviruses: Highly active antiretroviral therapy (HAART)
– Protease inhibitors
– Reverse transcriptase inhibitors
– Attachment and fusion inhibitors
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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Nursing Process: Implementation (cont.)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
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Nursing Process: Implementation (cont.)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
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Nursing Process: Implementation (cont.)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
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Nursing Process: Implementation (cont.)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
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Nursing Process: Implementation (cont.)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
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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
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QuestionQuestion
• Is the following statement true or false?
• A virus is larger than a bacterium.
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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.
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QuestionQuestion
• Is the following statement true or false?
• In most situations, antivirals have major adverse reactions.
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AnswerAnswer
• False
• In most situations, antivirals have minor adverse reactions such as gastrointestinal disturbances or flu-like symptoms.
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
QuestionQuestion
• Is the following statement true or false?
• Antiretroviral drugs are used primarily to reduce viral load in patients with HIV.
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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).