971.Which is incorrect
A.Phenytoin follows zero order kinetics
B.At high doses alcohol has 1storder kinetics
C.Rifampicin enhances oestrogen metabolism
D.Low dose paracetamol is mainly metabolized by the cytochrome p450 system
E.Hepatic carcinoma tends to inhibit drug metabolism

972.Volume of distribution
A.Never exceeds total body volume
B.Relates loading dose to the target concentration
C.If high, suggests the drug is highly protein bound
D.If low suggests the drug is hydrophobic
E.Relates clearance to the plasma concentration

973.Clearance
A.is the amount of drug excreted per minute
B.is limited by blood flow if a tissue has a high extraction ratio
C.is required to calculate the loading dose
D.is constant for all the doses of phenytoin
E.inthe kidney is determined by the GFR alone

974.Volume of distribution equals
A.dose / plasma concentration
B.amount of drug / plasma concentration
C.urine concentration / plasma concentration
D.dose / urine concentration
E.plasma concentration / urine concentration

975.Half life is equivalent to
A.The time between 2 consecutive doses
B.The time taken for the drug to be eliminated
C.The time to reach steady state
D.The time taken for the plasma concentration to fall to 50%
E.The time taken for the kidney to clear half the dose given

976.Which is not a phase I metabolizing reaction
A.acetylation
B.deanimation
C.hydrolysis
D.oxidation
E.reduction

977.Bioavailability of drugs is
A.100% for IM
B.100% for PO which are not metabolized by the liver
C.equal to the amount of drug in the body at the time of peak plasma concentration relative to the amount administered
D.important because it determines the fraction of the dose administered which can be found in the systemic circulation
E.less than 100% only in orally administered drugs

978.A patient has taken an OD of a drugwith a pKa of 9, which is true?
A.Urinary excretion would be accelerated by giving NaHCO3
B.More of the drug will be in its unionized form in the stomach than in the jejunum
C.Gastric lavage should be performed immediately to punish the patient for wasting yourtime
D.Haemodialysis should be carried out immediately
E.Administration of NH4Cl will increase urinary excretion

979.All of the following can be metabolized to toxic metabolites except
A.Paracetamol
B.Ethylene glycol
C.Pethidine
D.Methanol
E.Polyethylene glycol

980.Which istrue of protein binding
A.The fraction of unbound drug is determined by the affinity of the drug for the protein, the concentration of the binding protein and the molecular weights of the drug and the protein
B.α1-acid glycoprotein has little effect on the binding of drugs in plasma
C.in general, changes in protein binding do not cause clinically important drug interactions
D.protein binding refers to an irreversible interaction of drugs with proteins in the plasma
E.drugs only slowly bind and/or dissociate from plasma proteins

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