Antiretroviral Drugs MCQs

NACO recommends a combination of 2NRTI+protease inhibitor for treatment of HIV-2 infection. Currently, the first line regimen consists of Tenofovir +Lamivudine +lopinavir -ritonavir Reference : Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, page 335

Hepatitis B virus infected patients on lamivudine therapy may develop resistance to the drug due to mutation in the YMDD locus present in the HBV reverse transcriptase region of polymerase gene. Pre-core mutants have mutations in pre-core region (which abolishes HBeAg production) or basal core promoter region (down regulates HBeAg production). The escape mutants of HBV have mutations in the S gene ("a" antigen region) which leads to alteration of HBsAg. Reference : Bailey and Love's Short Practice of Surgery, 28th Edition, Chapter: 20, Pg: 279

Post-exposure prophylaxis: Treatment should be started within 72 hours of exposure, preferably as early as possible At first the wound is washed with soap and water. Secondly before initiating drug therapy blood samples are taken to measure the baseline viral markers Then, triple drug therapy is given which includes Tenofovir, Lamivudine and a boosted protease inhibitor for 28 days. After 6 weeks again viral markers are measured to check for the infection.

Ritonavir being a potent CYP3A4 inhibitor acts as a booster for other antiretrovirals like Saquinavir. Ritonavir (RTV) It is a potent PI; also a potent CYP3A4 inhibitor. Drug interactions, nausea, diarrhoea, paresthesias, fatigue and lipid abnormalities are prominent. Though RTV (600 mg twice daily) can be used as an antiretroviral drug, it is more commonly employed in a low dose (100 mg BD) to boost all other PIs except NFV. Low dose RTV produces no additional side effects. CYP enzymes inducers & inhibitors Mnemonic Enzyme inhibitors [ Virat Kohli Can't Call Every Indians ] V alproate K etoconazole C imetidine C iprofloxacin/ C larithromycin E rythromycin I NH Enzyme Inducers [GPRS Cell Phone] G - Griseofulvin P - Phenytoin R - Rifampicin S - Smoking Cell - Carbamazepine Phone - Phenobarbitone

Tenofovir is often co-administered with emtricitabine, and a once-daily, fixed-dose combination formulation is available, either alone or in combination with efavirenz. A recent placebo controlled. study found that use of emtricitabine and tenofovir was effective as pre-exposure prophylaxis, reducing HIV acquisition in men who have sex with men. In another placebo-controlled study, use of the experimental 1% tenofovir gel as a vaginal microbicide was effective in decreasing the incidence of heterosexual HIV acquisition. Reference : LANG’ Basic & clinical pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor 12 th edition. Chapter 49- Antiviral Agents by Dr. Sharon Safrin,MD. Page no. 875

HBV infection in the United States: five oral nucleoside/nucleotide analogues (lamivudine, adefovir dipivoxil, tenofovir, entecavir, telbivudine) and two injectable interferon drugs (interferon alfa-2b, pegylated interferon alfa-2a) Reference LANG’ Basic & clinical pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor 12 th edition. Chapter 49- Antiviral Agents by Dr. Sharon Safrin,MD. Page no. 883

Six classes of antiretroviral agents are currently available for use: nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), fusion inhibitors, CCR5 receptor antagonist integrase inhibitors. Reference : LANG’ Basic & clinical pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor 12 th edition. Chapter 49- Antiviral Agents by Dr. Sharon Safrin,MD. Page no. 869

Lamivudine is often co-administered with abacavir, and a once-daily, fixed-dose combination formulation is available. Lamivudine is also available in a fixed-dose combination with zidovudine, either alone or in combination with abacavir. Reference : LANG’ Basic & clinical pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor 12 th edition. Chapter 49- Antiviral Agents by Dr. Sharon Safrin,MD. Page no. 874