Zidovudine Comprehensive Study Guide With Accurately Solved Questions.
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Course
AZT
Institution
AZT
Pharmacotherapeutics - correct answer Zidovudine is active against the Epstein-Barr virus and hepatitis B virus (HBV) and exerts some antibacterial activity against Enterobacteriaceae, but its main indication is for treating HIV infection in adults and ...
Pharmacotherapeutics - correct answer Zidovudine is active against the
Epstein-Barr virus and hepatitis B virus (HBV) and exerts some antibacterial activity against
Enterobacteriaceae, but its main indication is for treating HIV infection in adults and children and
preventing transmission on HIV to the fetus in pregnant HIV positive women. The symptomatic patients
should start therapy regardless of laboratory values. The recommendation for initiating treatment in
asymptomatic patients is a CD4 cell count between 200-350 cell/mm, or those with HIV nephropathy, or
patients with active HBV with the intent to treat HBV.
Pharmacokinetics - correct answer Zidovudine (AZT) is administered orally or
parenterally. Following oral administration, zidovudine is absorbed rapidly from the tract. The rate and
extent of drug absorption may be decreased by fatty meats. The half-life of zidovudine is 1 hour in
patients with normal renal function and increases to 1.4 to 2.9 hours in patients with renal dysfunction.
Hepatic dysfunction also causes a moderate prolongation of zidovudine half-life. It crosses the blood
brain barrier and placenta. It is converted into zidovudine triphosphate, its active form, by intracellular
conversion and irs inactive metabolite by the liver. Both active drug and inactive metabolite are excreted
by glomerular filtration and tubular secretion. It is now available in fixed dose combination in one pill,
with lamivudine or abacavir.
Pharmacodynamics - correct answer Zidovudine inhibits the synthesis of DNA
by reverse transcriptase Zidto ovudine bears a structural resemblance to thymidine, a natural
nucleoside. Reverse transcriptase fails to distinguish zidovudine from its natural counterpart, and the
enzyme attempts to use the drug to synthesize vial DNA. When zidovudine is incorporated into a stand
of DNA, the addition of further nucleotides is blocked, and the full length viral DNA chain is prematurely
terminated.
Contraindications and Precautions - correct answer Absolute contraindications
to the use of zidovudine include hypersensitivity, breast-feeding, and existing lactic acidosis. Patients
with preexisting hepatic dysfunction, obesity, and prolonged nucleoside analogue therapy have a higher
risk of developing lactic acidosis due to the association of NRTIs to liver mitochondrial toxicity.
Zidovudine should be given with caution to patients with pre-existing depression of bone marrow
function, folate deficiency, or vitamin B12 deficiency. Patients with these disorders are at increased risk
for severe hematologic toxicity. It is also given with caution to patients who have recently received
cytotoxic drugs or radiation therapy because it may induce myelosuppression. Because of the risk of
myelosuppression, patients with dental disease are also given zidovudine with caution. Zidovudine
should be given with caution in patients with hepatic or renal disease. In patients with impaired hepatic
function or renal function, it may accumulate.
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