Q- Which one of the following medications can be used safely in a case of hepatic cirrhosis or liver failure?
A- Fluoxetine
B- Lorazepam
C- Metronidazole
D- Warfarin
B- Lorazepam- It is the only one on the list that is conjugated extrahepatically so, it is not metabolized by hepatic cytochrome P450.
Q- Morphine is NOT used in which one of the following conditions due to its unwanted effect on the involved organ?
A- Biliary pain
B- Myocardial infarction
C- Post-appendicectomy
D- Pulmonary congestion
A- Biliary pain- Morphine is not used in biliary pain because it causes contraction of the sphincter of Oddi leading to spasms. It is recommended in MI and pulmonary congestion due to its vasodilating and sedative actions.
Q- Which one of the following medications inhibits folic acid synthesis through inhibition of dihydropteroate synthetase?
A- Ciprofloxacin
B- Pyrimethamine
C- Sulfonamides
D- Trimethoprim
C- Sulfonamides- It is used in combination with trimethoprim due to multiple resistance when used alone. Sulfasalazine is used in rheumatoid arthritis and ulcerative colitis. Ciprofloxacin is not an inhibitor of folic acid synthesis. Trimethoprim and pyrimethamine inhibits dihydrofolate reductase.
