Pharmacology of Antimicrobials and Cytotoxic drugs
1. Metronidazole:
a. T
b. T
c. T
d. T: in anaerobes, metronidazole is reduce to its nitro group which binds to DNA and prevents nucleic acid formation.
2. Sulfonamides:
a. T
b. T
c. T
d. T
3. Sulfamethoxazole:
a. F: it is a structural analogue of PABA.
b. F: it is a competitive inhibitor of dihydropteroic synthetase responsible for incorporation of PABA into dihydrofolic acid.
c. T: it is present together with trimethoprim in the ratio of 5: 1.
d. T: this interferes with the bacterial synthesis of folic acid and decreases DNA synthesis; mammalian cells are not affected as they can utilize extracellular folate.
4. Gentamicin:
a. T: binds to 30S ribosome causing the wrong amino acid to be inserted into the growing peptide chain resulting in formation of malfunctional bacterial proteins.
b. T: accumulates in renal failure.
c. F
d. T: aminoglycosides form complex in vitro with penicillins resulting in a decrease in clinical potency.
5. Adverse effects of chloramphenicol:
a. T
b. T: potentially fatal reaction occurring in premature infants and neonates, present with vomiting, abdominal distension and circulatory collapse.
c. T
d. F
6. Penicillin G:
a. T
b. F: bactericidal, binds to PBP in cell wall, blocking cell wall synthesis.
c. T: other modes of resistances are lack of PBP in cell wall, reduced affinity to PBP and impermeability of cell wall.
d. usually given IV / IM; penicillin V is given orally.
7. The mechanism of the following antibiotics are as indicated:
a. T
b. T
c. T
d. T
8. Hypersensitivity reactions to penicillin:
a. T
b. F
c. F
d. T: anaphylaxis, which occur in 0.05% of users.
9. Rifampicin:
a. T: is active against both intracellular and extracellular mycobacteria.
b. F: binds to DNA-dependent RNA polymerase and suppresses initiation of chain formation.
c. T
d. T
10. Isoniazid:
a. T: it is a liver microsomal enzyme inhibitor.
b. T: used in TB meningitis.
c. T: forms complexes with pyridoxal phosphate, inhibiting formation of nicotinic acid from tryptophan - symptoms are diarrhea, dermatitis and dementia.
d. T.