Pharmacokinetics of two rectal dosage forms of ketoprofen in patients after anal surgery.

Two kinds of dosage forms of commercially available suppositories containing ketoprofen (KP), fatty suppositories (FS) and gelatin capsulated suppositories (GCS), were administered to patients immediately after anal surgery, and results obtained were compared. No difference was found in each corresponding pharmacokinetic parameter of the two dosage forms. However, when these parameters were compared with those from healthy subjects, significant differences were found in the values of peak level (Cmax), peak time (Tmax) and terminal phase half-life (t1/2). Cmax decreased by one half, and Tmax and t1/2 increased two and four times longer, respectively, those from healthy subjects. The absorption rate constant (ka) in patients was significantly (p less than 0.01) smaller than that in healthy subjects. However, the distribution volume/bioavailability (Vd/F), elimination rate constant (kel), and area under the curve (AUC) differed only slightly. Consequently, the flip-flop phenomena could be seen in the time profiles of plasma KP concentration of patients. These results suggested that the rectal suppository of KP should be administered with care, especially in the patients operated on under spinal anesthesia.