Reference

Drug/poly(vinylpyrolidone) coprecipitates: kinetics of drug release and formation of supersaturated solutions

Drug/poly(vinylpyrolidone) coprecipitates: kinetics of drug release and formation of supersaturated solutions. Merkle, Hans P. (Inst. Pharm. Technol. Biopharm., Univ. Heidelberg, Heidelberg 6900, Fed. Rep. Ger.). Proc. Int. Symp. Povidone, 202-16. Edited by: Digenis, George A.; Ansell, Jay. Univ. Ky., Coll. Pharm.: Lexington, Ky. (English) 1983. CODEN: 52WBAM. DOCUMENT TYPE: Conference CA Section: 63 (Pharmaceuticals) The kinetics of drug release from drug-poly(vinylpyrrolidone) [9003-39-8] coppts. and the state of drugs under extreme supersatn. following the dissoln. of coppts. are discussed. Kollidons 17, 25 and 30 with mean mol. wts. 11,500, 25,000 and 40,000 were used. Drugs used were hydrocortisone [50-23-7], prednisone [53-03-2], clonazepam [1622-61-3], nitrazepam [146-22-5], flunitrazepam [1622-62-4], and salicylic acid [69-72-7]. An increase in mol. wt. of the polymer shows decreased release rates with the max. release rates remaining const. for all polymer used. With a higher mol. wt. polymer, a higher drug wt. fraction is required to obtain the same release rates. Studies with copptd. salicylic acid did not demonstrate the same release pattern. Even at low drug wt. fractions, the deviation between predicted and exptl. data was marked indicating a different release mechanism. Drastic deviations occurred when the release was performed at pH 1.2. This suggests a pH-dependent drug/polymer interaction interfering with the polymer dissoln. Thus, the fast drug release from coppts. depends on an essentially free dissoln. of its polymeric carrier. By using equil. dialysis studies and polarog. of supersatd. solns. it was shown that for coppt. action the ability to sustain high supernatant levels following dissoln. was equally important.

Tablet weight and biopharmaceutical properties variations

Tablet weight and biopharmaceutical properties variations. Colombo, P.; Caramella, C.; Conte, U.; Gazzaniga, A.; La Manna, A. (Dip. Chim. Farm., Univ. Pavia, Pavia 27100, Italy). Biopharm. Pharmacokinet., Eur. Congr., 2nd, Volume 1, 512-20. Edited by: Aiache, J. M.; Hirtz, J. Lavoisier: Paris, Fr. (English) 1984. CODEN: 53JFAA. DOCUMENT TYPE: Conference CA Section: 63 (Pharmaceuticals) Studies of the relations among wt., compression force, and dissoln. rate of prednisone (I) [53-03-2] tablets showed the dependence of dissoln. rate on tablet wt. variations. The selection of tablets of identical wt. or the compression of different wts. at the same force, allows producing a batch having a uniform mean dissoln. time. An instrumented reciprocating machine was used to correlate tablet characteristics with compression force, and an industrial rotating machine to produce a pilot batch to study the dissoln. rate distribution as a function of wt. variation.