119,316 research outputs found
Alternative means of shelter delivery in developing countries : a cooperative approach
Get PDFThesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1982.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Bibliography: leaves 147-152.by Felton L. Lamb, Jr.M.S
Inscribed portrait of Senator George L. Radcliffe.
No full textHandwritten inscription: \u27To my friend Felton M. Johnston with pleasantest of reflections and best of wishes - George L. Radcliffe\u27https://egrove.olemiss.edu/fmjohnston/1081/thumbnail.jp
Gastroresistant coating of HPC capsules prepared by Injection-Molding
No full textPulsatile release capsules made of a swellable/ erodible polymer (HPC), prepared by injection molding, were preliminarily evaluated as substrates in coating processes. The feasibility of the process was demonstrated with Eudragit® L 30 D-55 by comparing the application of the same coating suspension onto conventional gelatin and HPMC capsules. The gastroresistant capsular devices obtained showed promising results for the development of a time-controlled colonic drug delivery system
A-1367a: 370 East Main Street, Hyrum, Utah, George L. Felton residence. Lot 7 Block 22 Plat D. 1957
No full textA-1367a: 370 East Main Street, Hyrum, Utah, George L. Felton residence. Lot 7 Block 22 Plat D. 1957 (2 photos
Enteric-coating of HPC capsules prepared by Injection-Molding
No full textPurpose.
To evaluate injection molded (IM) hydroxypropyl cellulose (HPC)-based capsules as cores for the application of a pH-dependent soluble coating, in comparison with conventional capsules.
Methods
IM (BabyPlast 6/10P, Cronoplast S.L.) formulation consisted of a 90:10 HPC (Klucel® LF, Ashland):polyethylene glycol 1500 blend. Size 0 gelatin and hydroxypropyl methylcellulose (HPMC) capsules (Capsugel) and the IM HPC-based capsules were filled with 80 mg of acetaminophen. Aqueous solutions of the same materials were used for sealing the capsule shells. Capsules were coated (Hi-coater, Vector Corporation LDCS, equipped with a perforated pan) with a Eudragit® L 30 D55 (64.10):TEC (3.85):deionized water (32.05) suspension. Samples of sealed and unsealed capsules with theoretical weight gains of 0, 4, 6, 8, 10 mg of dry polymer/cm2 were withdrawn and imaged by scanning electron microscopy (SEM). The Dissolution Test for Delayed-Release Dosage Forms (USP 34) was used for evaluating the release performance and the amount of drug released was determined by UV/Vis spectrophotometry at 248 nm.
Results
Initially gelatin, HPMC and HPC were coated simultaneously in a single pan; actual polymer deposition was not linear to theoretical weight gain likely due to different capsules shell weight and so HPC ones were coated separately (same coating parameters). The release performance demonstrated no need for sealing the HPC-based cores. Different from gelatin and HPMC capsules, the lag time (time to 10% drug release) from HPC ones increased as a function of the amount of polymer applied, up to ~168 min; moreover, samples with the maximum level of coating were able to withstand the acidic medium and release the drug after the pH change within a time analogous to the lag time of uncoated IM cores.
Conclusion
Molded HPC-based capsules could successfully coated with an enteric polymer; this gastroresistant pulsatile-delivery device has promise for further developing into a colonic delivery system
Enteric-coating of pulsatile-release capsules prepared by injection molding
No full textPurpose.
To evaluate hydroxypropylcellulose (HPC)-based capsular devices prepared by injection molding (IM) as substrates for the application of a gastroresistant coating, in comparison with conventional capsules.
Methods.
Capsules were prepared by IM (BabyPlast 6/10P, Cronoplast S.L.) from a 90:10 HPC (Klucel® LF, Ashland):polyethylene glycol 1500 blend. HPC-based, commercially available size 0 gelatin and HPMC capsules (Capsugel) were filled with 80 mg of acetaminophen. Samples of the three types of capsules were manually sealed with aqueous polymer solutions of the same shell material. Coating suspension (weight %): Eudragit® L 30 D55 (64.10), TEC (3.85) and deionized water (32.05). A Hi-coater (Vector Corporation LDCS) equipped with a perforated coating pan was used. Samples with theoretical weight gains of 4, 6, 8, 10 mg of dry polymer/cm2 were withdrawn during the coating process. Scanning electron microscopy (SEM) images were taken of the coated and uncoated capsules. The release performance was evaluated according to USP 34 (Dissolution Test for Delayed-Release Dosage Forms) and the amount of drug released was determined by UV/Vis spectrophotometry at 248 nm.
Results.
IM capsules showed a surface rougher than that of gelatin and similar to that of HPMC ones; hence, acceptable adhesion properties of the coating film onto the cores could be expected like for traditional HPMC cores. Indeed, a good correspondence between the actual and the theoretical amount of applied polymer was achieved by adjusting process conditions. A sealing step was not required to achieve enteric resistance. The lag time of coated HPC-based systems increased with respect to that of uncoated cores (̴ 40 min) and was further increased with higher amounts of polymer applied. For the systems coated up to the maximum level, the ability to withstand the acidic medium was confirmed. Moreover, their lag time (~168 min) seems compatible with the maintenance of a release behavior after the pH change analogous to that of the uncoated IM cores.
Conclusion.
The possibility of obtaining a gastroresistant pulsatile-delivery device based on IM capsules was demonstrated. This approach is promising for the development of time-dependent colonic delivery systems
Enteric-coating of pulsatile-release HPC capsules prepared by injection molding
No full textCapsular devices based on hydroxypropyl cellulose (Klucel® LF) intended for pulsatile release were prepared by injection molding (IM). In the present work, the possibility of exploiting such capsules for the development of colonic delivery systems based on a time-dependent approach was evaluated. For this purpose, it was necessary to demonstrate the ability of molded cores to undergo a coating process and that coated systems yield the desired performance (gastric resistance). Although no information was available on the coating of IM substrates, some issues relevant to that of commercially-available capsules are known. Thus, preliminary studies were conducted on molded disks for screening purposes prior to the spray-coating of HPC capsular cores with Eudragit® L 30 D 55. The ability of the polymeric suspension to wet the substrate, spread, start penetrating and initiate hydration/swelling, as well as to provide a gastroresistant barrier was demonstrated. The coating of prototype HPC capsules was carried out successfully, leading to coated systems with good technological properties and able to withstand the acidic medium with no need for sealing at the cap/body joint. Such systems maintained the original pulsatile release performance after dissolution of the enteric film in pH 6.8 fluid. Therefore, they appeared potentially suitable for the development of a colon delivery platform based on a time dependent approach
Influence of temperature and relative humidity conditionsonthe pan coating of hydroxypropyl cellulose molded capsules
No full textIn a previous study, hydroxypropyl cellulose (HPC)-based capsular shells prepared by injection molding and intended for pulsatile release were successfully coated with 10 mg/cm2 Eudragit® L film. The suitability of HPC capsules for the development of a colon delivery platform based on a time dependent approach was demonstrated. In the present work, data logging devices (PyroButton®) were used to monitor the microenvironmental conditions, i.e. temperature (T) and relative humidity (RH), during coating processes performed under different spray rates (1.2, 2.5 and 5.5 g/min). As HPC-based capsules present special features, a preliminary study was conducted on commercially available gelatin capsules for comparison purposes. By means of PyroButton data-loggers it was possible to acquire information about the impact of the effective T and RH conditions experienced by HPC substrates during the process on the technological properties and release performance of the coated systems. The use of increasing spray rates seemed to promote a tendency of the HPC shells to slightly swell at the beginning of the spraying process; moreover, capsules coated under spray rates of 1.2 and 2.5 g/min showed the desired release performance, i.e. ability to withstand the acidic media followed by the pulsatile release expected for uncoated capsules. Preliminary stability studies seemed to show that coating conditions might also influence the release performance of the system upon storage
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