MDS PREP
Chlortetracycline acts by interfering with
1. protein synthesis on bacterial but not mammalian ribosomes
2. cell wall synthesis
3. nucleic acid synthesis
4. protein synthesis on mammalian but not bacterial ribosomes
Pharmacology
Answer: 1
Chlortetracycline acts by interfering with protein synthesis on bacterial but not mammalian ribosomes
Drugs mostly cross biological membranes by
1) Passive diffusion
2) Active diffusion
3) Active transport
4) Carrier mediated transport
Pharmacology Answer: 1
Passive diffusion: The movement of drug across a membrane in a manner driven solely by the concentration gradient. In passive diffusion, drug moves from a region of greater concentration to a region of lesser concentration.
Which of the following drugs have a narrow therapeutic index?
1) Lithium
2) Diazepam
3) Penicillin
4) Desipramine
Pharmacology Answer: 1
Other drugs with narrow therapeutic index:
Digoxin Gentamicin Amphotericin B Levothyroxine Prazosin Theophylline Quinidine Warfarin Valproic acid
All of the following drugs cross the placenta except?
1) Phenytoin
2) Diazepam
3) Morphine
4) Heparin
Pharmacology Answer: 4
Heparin Heparin does not the cross the placenta.
Hence its safe for use in pregnant patients who need anticoagulation.
The penicillin with the best gram negative spectrum is
1. methicillin
2. phenethicillin
3. ampicillin
4. penicillin V
Pharmacology
Answer: 3
The penicillin with the best gram negative spectrum is ampicillin
In Dicumarol poisoning which Vit K is used
1) Menadione
2) Menaqunone
3) Phytonadione
4) None of the above
Pharmacology Answer: 3
To reverse the effect of overdose of oral anticoagulants:
Phytonadione (K1) is the preparation of choice, because it acts most rapidly, dose depends on the severity of upoprothrombinemia & bleeding.
Developed hypo reactivity to a drug is
1) Detoxification
2) Antagonism
3) Tolerance
4) Desensitization
Pharmacology Answer: 3
Tolerance: The capacity to absorb a drug continuously or in large doses without adverse effect; diminution in the response to a drug after prolonged use.
Clinically significant drug interaction occurs between pyridoxine and all the following drugs except?
1) Isoniazid
2) Cyclosporine
3) Levodopa
4) Hydralazine
Pharmacology Answer: 2
Pyridoxine – drug interactions :
INH – induces a pyridoxine deficiency state
Levodopa – pyridoxine promotes peripheral conversion of levodopa to dopamine – thus it decreases therapeutic action of levodopa in the brain
Oral contraceptive pills – decrease pyridoxine levels in some females
Hydralazine – impairment of pyridoxine utilisation
4-deoxy pyridoxine – pyridoxine antagonist