Single doses of 1 gm 5-aminosalicylic acid (5-ASA) suspension was administered to 24 healthy volunteers during both fasting and fed conditions. For subjects in a fasting state, plasma 5-ASA and acetyl 5-ASA concentrations peaked rapidly 1 hour after dosing to 14.72 micrograms/ml and 11.4 micrograms/ml, respectively. The elimination half-life of 5-ASA was 51.9 minutes, whereas the acetyl 5-ASA half-life could not be determined. A mean of 78.3% of the dose was excreted in the urine, with 5-ASA accounting for 21.2% of the dose and acetyl 5-ASA accounting for the balance. Only 11.3% of the dose was eliminated in the feces, consisting mostly of acetyl 5-ASA. Food coadministration reduced 5-ASA and acetyl 5-ASA systemic relative bioavailability to 44% and 76%, respectively, compared with the fasting treatment. Urinary excretion of the salicylates was reduced to 46.8%, and fecal salicylate elimination increased almost 100%--to 24.2% of the total dose.

One gram single dose of Pentasa controlled-release capsules was administered to 24 healthy volunteers under fasting condition. Mean plasma 5-aminosalicylic acid (5-ASA) and acetyl 5-ASA concentrations peaked at 0.53 microgram.ml-1 and 1.33 micrograms.ml-1 from 3 to 4 hours following dosing, respectively. The half-lives of both compounds could not be determined as absorption of 5-ASA was continuous throughout the gastrointestinal tract. An average of 29.4% (CV: 27%) of the dose was excreted in the urine primarily as acetyl 5-ASA. Up to 91.1% of the dose was released from the capsules. Forty percent of the dose (CV: 40%) was eliminated in the feces, with 8.9% of the dose remained as formulation bounded 5-ASA, indicating that controlled-release capsules continue to release drug throughout the GI tract. 5-ASA contributed 46.7% of the salicylates eliminated in the feces and acetyl 5-ASA accounted for the balance. Controlled-release capsules produced three times more total salicylates and 10 times more total and free 5-ASA in the feces than did 5-ASA suspension. Thus, while lower systemic levels of salicylates were absorbed, greater therapeutic quantities of 5-ASA were available in the bowel.

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A sensitive and selective liquid chromatographic procedure to quantitate the deflazacort metabolite 21-hydroxy-deflazacort (DF-21OH) in human plasma was developed and validated. DF-21OH and fludrocortisone acetate (internal standard, IS) were isolated from human plasma (2 mL) by solid-phase extraction onto C-18 cartridges. Potential interferences were selectively removed and analytes were eluted with ethyl acetate. Following evaporation, the residue was reconstituted for HPLC analysis. Separation was achieved by gradient elution using a 5 microns YMC Basic column (2.0 x 100 mm) with mobile phases consisting of 20% methanol and 50% acetonitrile in 50 mM phosphate buffer (pH 3) at a temperature of 50 degrees C. Flow rate was maintained at 0.3 mL/min., and analytes were quantified spectrophotometrically at 246 nm. The assay was validated over the range 1.0 to 500 ng/mL DF-21OH. Calibration curves were prepared using a weighted (1/concentration) nonlinear quadratic regression algorithm. Peak-height ratios were proportional to the amount of DF-21OH added to plasma. Assay precision (%RSD) ranged from 4.2 to 11%, with a corresponding assay accuracy (% relative error) of +/- 2.8%. Absolute recovery of DF-21OH from plasma was 78-86% over the concentration range. The minimum quantitation limit was 1.0 ng/mL.