Q: The rectal route of administration may be preferred over the oral route for some systemic-acting drugs because
Explanation: Although it is desirable for certain drugs rapidly metabolized by the liver to bypass absorption into the portal circulation, the value of using the rectal route for this pur- pose is limited. This is due to the fact that whereas three principal veins drain the blood supply to the rectum, only the middle and inferior hemorrhoidal veins actually bypass theliver. The superior hemorrhoidal vein enters the portal circulation via the inferior mesenteric vein.
Q: The volume of distribution (Vd) of a particular drug will be
Explanation: Following a given dose of a drug, the greater its concentration in various tissue compartments, the smaller its concentration in plasma. Therefore, according to the rela- tionship Ab = Vd Cb , the Vd of a particular drug will be greater for those drugs that tend to con- centrate in tissues as opposed to plasma.
Q: What maintenance dose is appropriate in the above patient if the clearance is estimated to be .35 mL/min/kg?
Explanation: onverting the clearance to L/hr and eliminating the kg weight, .35 mL/min/kg x 60 min/hr x 70 kg = 1470 mL/hr or 1.47 L/hr (F) (Maintenance dose) = (Plasma Cone.) (Clearance) (.85) x= (10 mg/L) (1.47 L/hr) x= 17.3 mg per hour
Q: Bioavailability and pharmacokinetic data either is or may be required when pharmaceutical companies submit I. new drug applications II. abbreviated new drug applications III. supplemental applications
Explanation: Unless a special waiver is granted, the FDA expects to see human bioavailability and pharmacokinetic data on all applications. Possible exceptions will be for intravenous solutions, topicals, and inhalation products.