15. Clinical Pharmacokinetics I Flashcards
A doctor is trying to figure out what the appropriate loading dose of “Drug X” for a patient. When 100mg of Drug X is in the body 50mg is in the plasma. The target concentration is the doctor is trying to reach is 200 mg. What is the loading dose the doctor should give?
A. 100mg B.400 mg C. 200mg D.300mg E. 600mg
RFA
Ans B. Loading Dose= target x Vd
Vd= total in body/ plasma concentration
100/50=vd Vd=2
target=200mg
200x2=400 mg= Loading Dose
An 55 year old obese man is prescribed “Drug X”. Since the man is obese what should the physician taken account for.
A. Effects Vd decreasing half life B.Effects CL increasing half life C. Effects Vd increasing half-life D. Effects Vd decreasing half-life E. No effect
RFA
Ans. C Effects Vd increasing half life, this would also be seen in patients with pathologic fluid
A. Effects Vd decreasing half life- we have no example
B. Effects Cl Increasing half life- Ageing, CYP inhibition, Cardiac failure, Liver failure, Renal Failure
D. Effects Vd decreasing half-life- CYP induction
E. No effect- just needed a 5th choice
Drug Z recently received FDA approval for treating familiar stupidity. Your patient comes from a long line of dipshits and you give the patient a loading dose of 1000mg/L IV bolus. The volume of distribution is 5L. What is the target concentration you are trying to establish for the patient?
A. 800 mg B. 500 mg C. 1000 mg D. 200 mg E. 300 mg
SZ
Ans. 200 mg
TC = loading dose/volume of distribution TC= 1000/5 = 200
Why are zero order drugs very unpredictable when determining the therapeutic index?
A. They are eliminated by a constant fraction
B. The rate of elimination is proportional to drug concentration
C. Steady state is equal to 4 half lives
D. The rate of elimination is independent of drug plasma concentration
E. They are excreted by bile only
SZ
Ans. D
The rate of elimination is independent of drug plasma concentration
Choice A-C are characteristics of first order drugs.
