Review of Pharmacology - 9E (2015)

Review of Pharmacology
Chemotherapy B: Antimicrobials for Specific Conditions
105. Ans. (b) As reverse transcriptase inhibitor (Katzung 11/e p861-862)
106. Ans. (c) Nevirapine (Ref: Katzung 11/e p862)
Nevirapine and zidovudine are used to prevent vertical transmission of HIV from pregnant females to the baby.
107. Ans. (a) Raltegravir (Ref: Katzung, 11/e p866)
RalTERGRAvir is an inTEGRAse inhibitor used in HIV.
108. Ans. (a) Saquinavir (Ref: Katzung 11/e p58, 863)
All the drugs given in the options are microsomal enzyme inhibitors. Among protease inhibitors, ritonavir is the strongest inhibitor of
CYP3A4 enzymes whereas saquinavir is the weakest.
109. Ans. (d) Abacavir (Ref: KDT 6/e p772-773)
All drugs ending with navir are protease inhibitors. Abacavir is an NRTI.
110. Ans. (a) Didanosine (Ref: Katzung 11/e p858)
• All NRTIs can cause pancreatitis and peripheral neuropathy.
• Maximum risk of pancreatitis is associated with didanosine and maximum incidence of peripheral neuropathy is
seen with stavudine.
• Lamivudine is safest NRTI as it has minimum risk of pancreatitis and peripheral neuropathy.
111. Ans. (b) CYP3A4 inhibition by ritonavir (Ref: Katzung 10/e p810; KDT 6/e p773)
Ritonavir is a microsomal enzyme inhibitor particularly of CYP3A4. It decreases the metabolism of other drugs and thus
lower dose of lopinavir can be used in treatment of HIV when combined with ritonavir.
112. Ans. (a) Non-nucleoside reverse transcriptase inhibitor (NNRTI) (Ref: KDT 6/e p772)
113. Ans. (c) Stavudine (Ref: WHO recommendations to treat adult and adolescent HIV/76)
Stavudine has maximum incidence of peripheral neuropathy whereas didanosine is associated with maximum risk of
acute pancreatitis.
114. Ans. (c) Abacavir (Ref: KDT 6/e p767)
• All protease inhibitors end with ‘NAVIR’ like nelfinavir, saquinavir and ritonavir.
• Abacavir is an NRTI.
115. Ans. (a) Lamivudine (Ref: KDT 6/e p771, 772)
Emtricitabine and lamivudine are safest NRTIs. These are not associated with peripheral neuropathy or pancreatitis.
116. Ans (d) Saquinavir causes maximum induction of CYP3A4 (Ref: Katzung 10/e p808)
• All protease inhibitors are substrates of hepatic CYP 3A4 and thus undergo extensive oxidative metabolism
in liver.
• Several of these agents are also the inhibitor of CYP 3A4 and thus lead to drug interactions.
• Saquinavir inhibits CYP3A4 and do not induce it. It is weakest inhibitor of CYP3A4 among protease inhibitors
• These act as the substrate for P-glycoprotein.
117. Ans. (a) Mutation at reverse transcriptase (Ref: KDT 6/e p770, 771)
Zidovudine is a nucleoside reverse transcriptase inhibitor, which is a viral enzyme. HIV undergoes mutations in this enzyme
to become resistant to NRTIs.
118. Ans. (a) Nausea and vomiting; (b) Anaemia; (c) Steatosis (Ref: KDT 6/e p771)
• Anaemia and neutropenia are the most important and dose related adverse effects of zidovudine.
• Nausea, anorexia, abdominal pain, headache, insomnia and myalgia are common at start of therapy but diminishes
later.
• Myopathy, lactic acidosis, hepatomegaly with steatosis, convulsion, and encephalopathy are infrequent.
[Harrison 17th/1954-1955
119. Ans. (a) Zalcitabine; (d) Stavudine (Ref: KDT 6/e p767)
120. Ans. (a) Interacts with terfenadine; (b) G.I. symptoms are seen (Ref: CMDT 2010/1229; KDT 6th /773)
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