PubMed · 10839527
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G Iddan, G Meron, A Glukhovsky, P Swain. 2000-05-25. Wireless capsule endoscopy.. https://doi.org/10.1038/35013140
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The enteric coating of HPMC capsules containing paracetamol was investigated. Two enteric polymers, Eudragit L 30 D-55 and Eudragit FS 30 D were studied, which are designed to achieve enteric properties and colonic release, respectively. The capsules were coated in an Accela Cota 10, and, as shown by optical microscopy, resulted in capsules with a uniform coating. Scanning electron microscopy of the surface of the capsules illustrate that, in contrast to gelatin, HPMC has a rough surface, which provides for good adhesion to the coating. Dissolution studies demonstrated that capsules coated with Eudragit L 30 D-55 were gastro resistant for 2 h at pH 1.2 and capsules coated with Eudragit FS 30 D were resistant for a further 1 h at pH 6.8. The product visualisation technique of gamma scintigraphy was used to establish the in vivo disintegration properties of capsules coated with 8 mg cm(-2) Eudragit L 30 D-55 and 6 mg cm(-2) Eudragit FS 30 D. For HPMC units coated with Eudragit L 30 D-55, complete disintegration occurred predominately in the small bowel in an average time of 2.4 h post dose. For HPMC capsules coated with Eudragit FS 30 D, complete disintegration did not occur until the distal small intestine and proximal colon in an average time of 6.9 h post dose.
A new simple and sensitive kinetic spectrophotometric method is described for analysis of nizatidine (I) and ranitidine (II). The method involves the reaction of the drugs with alkaline potassium permanganate, whereby a green color peaking at 610 nm is produced. The reaction is monitored spectrophotometrically by measuring the rate of change of absorbance of the resulting manganate species at 610 nm. Calibration graphs are linear over the concentration range 0.8-4.0 microg/ml and the precision (% RSD 1.80, 1.53 for I and II, respectively) is quite acceptable. The method is satisfactorily applied for direct analysis of pharmaceutical preparations containing I and II. A proposal of the reaction pathway is postulated.
For the sustained release formulation of recombinant human growth hormone (rhGH), dissociable rhGH aggregates were microencapsulated within poly(D,L-lactic-co-glycolic acid) (PLGA) microparticles. rhGH aggregates were first produced by adding a small volume of aqueous rhGH solution into a partially water miscible organic solvent phase (ethyl acetate, EtAc) containing PLGA. These rhGH aggregates were then microencapsulated within PLGA polymer phase by extracting EtAc into an aqueous phase pre-saturated with EtAc. Release profiles of rhGH from these microparticles were greatly affected by changing the volume of incubation medium. The released rhGH species consisted of mostly monomeric form having a correct conformation. This study reveals that sustained rhGH release could be achieved by microencapsulating reversibly dissociable protein aggregates within biodegradable polymers.