Session 15 pharmacology concerning drugs

Discription of Antivirals Drugs

1. Session 15: Description of Antiviral Drugs

2. : Indications, Dosage, Side Effects, Contraindications, Interactions Precaution of Acyclovir Antiviral drugs are a class of  medication  used for treating  viral infections   Indications Acyclovir is indicated to treat; Herpes simplex virus ( hsv ) infections Varicella-zoster virus ( vzv ) infections   Dose and Dosage Herpes Simplex Acyclovir (O) 400mg 8 hourly for 7 – 10 days   Herpes Zoster (Shingles) Acyclovir cream 5% applied until vesicles desapear . Plus Acyclovir (O) 800 mg 5 times a day until no new lesions appear

3. Side effects Nausea and vomiting, Abdominal Pain, Diarrhoea, Headache, Fatigue, Rash, urticaria and pruritus, Photosensitivity   Contraindications   Hypersensitivity to acyclovir or other related drugs

4. Interactions Interactions do not apply to topical aciclovir preparations Ciclosporin : increased risk of nephrotoxicity when aci - clovir given with ciclosporin Probenecid : excretion of aciclovir reduced by pro- benecid (increased plasma concentration) Precautions Maintain adequate hydration In renal impairment In elderly

5. Indications, Dosage, Side Effects, Contraindications, Interactions Precaution of Ganciclovir Indications Ganciclovir is used to treat cytomegalovirus (cmv) infections   Dose and Dosage By intravenous infusion, Initially (induction) 5mg/kg every 12 hours for 14–21 days for treatment   Side effects Diarrhoea, Nausea, Vomiting, Dyspepsia, Abdominal Pain, Constipation, Flatulence, Dysphagia, Taste Disturbance, Leucopenia , Thrombocytopenia,

6. Contraindications Hypersensitivity to ganciclovir , aciclovir , Abnormally low haemoglobin, neutrophil, or platelet counts   Interactions Probenecid : excretion of ganciclovir reduced by probenecid Hence increased plasma concentration and risk of toxicity   Precautions Close monitoring of full blood count Ensure adequate hydration during intravenous administration

7. Indications, Dosage, Side Effects, Contraindications, Interactions Precaution of Nucleoside Reverse Transcriptase Inhibitors Nucleoside Reverse Transcriptase Inhibitors (NRTIs) include:   Zidovudine (AZT) Lamivudine (3TC) Abacavir (ABC) Emtricitabine (FTC) Stavudine (d4T) Tenofovir (TDF) Tenofovir is classified as Nucleotide Reverse Transcriptase Inhibitor

8. Indications Nucleoside Reverse Transcriptase Inhibitors (NRTIs) are antiretroviral drugs that are indicated for treatment of HIV/AIDS in combination with other antiretrovirals   Dose and Dosage   Zidovudine (AZT) 300 mg PLUS Lamivudine (3TC) 150 mg twice daily   OR   Tenofovir (TDF) 300mg PLUS Lamivudine (3TC) 150 mg twice daily   Side effects Gastrointestinal disturbances (nausea, vomiting, abdominal pain, diarrhoea) Lactic acidosis Lipodystrophy Anaemia by Zidovudine Hypersensitivity by Abacavir Peripheral neuropathy by Stavudine Nephrotoxicity by Tenofovir

9. Contraindications Zidovudine is contraindicated to patients with Anaemia Patients who are hypersensitive to the NRTIs Tenofovir is contraindicated to patients with renal failure   Interactions Increased risk of haematological toxicity when Zidovudine given with NSAIDs Precautions Monitor liver function when using NRTIs Monitor renal function when using Tenofovir Monitor red blood cell count when using Zidovudine

10. : Indications, Dosage, Side Effects, Contraindications, Interactions Precaution of Non-Nucleoside Reverse Transcriptase Inhibitors Non-nucleoside reverse transcriptase inhibitors (NNRTIs) include: Nevirapine (NVP) Efavirenz (EFV).   Indications Non-nucleoside reverse transcriptase inhibitors are antiretroviral drugs used for the treatment of HIV/AIDS in combination with other antiretrovirals   Dose Efavirenz (EFV) 600 mg once daily at night. or Nevirapine (NVP) 200mg twice a day

11. Side effects Rashes due hypersensitivity reaction by Nevirapine CNS disturbances, abnormal dreams, hallucinations by Efavirenz     Contraindications Efavirenz and Nevirapine are contraindicated in patients with acute porhyria   Interactions Clarithromycin increase plasma levels of Efavirenz leading to increased risk of rash   Precautions Monitor liver function Close follow up when using Efavirenz inpatinets with history of mental illiness or seizures

12. : Indications, Dosage, Side Effects, Contraindications, Interactions Precaution of Protease Inhibitors Protease Inhibitors (PIs) include; Lopinavir (LPV) Atazanavir (ATV)   Indications Protease Inhibitors (PIs) are antiretroviral drugs used to treat HIV/AIDS combination with other antiretrovirals   Dose Lopinavir 800mg/Ritonavir 200mg   OR   Atazanavir 300mg/Ritonavir 100mg.

13. Side effects Gastrointestinal disturbances (nausea, vomiting, abdominal pain, flatulence) Lipodystrophy syndrome (fat redistribution, insulin resistance and dyslipidaemia) Fat redistribution presents as loss of subcutaneous fat, increased abdominal fat ‘buffalo hump’ and breast enlargement Blood disorders (anaemia, neutropenia and thrombocytopenia)   Contraindications PIs should not be given in patients with acute porphyria   Interactions Ritonavir inhibit Lopinavir metabolism and increase plasma concentration of Lopinavir   Precautions Monitor blood sugar when PIs are used in Diabetic patients as they are associated with hyperglycemia Monitor liver function

14. : Key Points Acyclovir is antiviral indicated for treatment of Herpes simplex virus ( hsv ) and varicella-zoster infections The use of Ganciclovir is associated with blood abnormalities therefore close monitoring of blood count is important Commonly used nucleoside reverse transcriptase include Zidovudine , Stavudine , Lamivudine and Stavudine Efavirenz , a non-nucleoside reverse transcriptase inhibitors should be cautiously in patients with history of mental illness and seizures Lopinavir is usually combined with another protease inhibitor Ritonavir, because it increases plasma concentration of Lopinavir to therapeutic levels.