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1.  Comparison of the formulation requirements of dosator and dosing disc automatic capsule filling machines 
AAPS PharmSci  2002;4(3):45-60.
The overall objective of this study was to provide ‘semi-quantitative’ or ‘rigorous’ definitions of the fluidity, lubricity and compactibility requirements of formulation for representative dosator and dosing disc capsule filling machines. To that end, model formulations were developed for those properties using Carr's compressibility index, ejection force, and plug breaking force at a specified compression force to gauge fluidity, lubricity, and compactibility, respectively. These formulations were each encapsulated on an Hofliger-Karg GKF-400 dosing disc machine and a Zanasi LZ-64 dosator machine. Each machine was instrumented to measure plug compression and ejection forces. The encapsulation process was evaluated for %CV of fill-weight, ejection force, plug breaking force and the dissolution of marker drugs incorporated in the formulations. The f2 metric was used to compare dissolution profiles. The results suggest: (1) formulations should meet different flow criteria for successful encapsulation on the two machines, (2) a relatively lower level of lubricant may be sufficient for the dosing disc machine, (3) a higher degree of formulation compactibility is needed for the dosator machine, and (4) transferring formulations between these machine types (same class, different subclass per FDA's SUPAC-IR/MR Manufacturing Equipment Addendum) could be challenging. In certain cases dissolution profiles for the same formulation filled on the two machines with equivalent compression force were different based on f2<50. Overall, the results of this study suggest a range of formulation characteristics appropriate for transferring formulations between these two types of machines.
PMCID: PMC2751356  PMID: 12423066
Capsules; Formulation; Flow; Compactibility; Lubrication; Filling Machines
2.  Selected physical and chemical properties of commercial Hypericum perforatum extracts relevant for formulated product quality and performance 
AAPS PharmSci  2001;3(4):1-18.
Objective. The complex composition-activity relationship of botanicals such as St John's Wort (SJW) presents a major challenge to product development, manufacture, and establishment of appropriate quality and performance standards for the formulated products. As part of a larger study aimed at addressing that challenge, the goals of the present study are to (1) determine and compare the phytochemical profiles of 3 commercial SJW extracts; (2) assess the possible impact of humidity, temperature, and light on their stability; and (3) evaluate several physical properties important to the development of solid dosage forms for these extracts. Methods. An adapted analytical method was developed and validated to determine phytochemical profiles and assess their stability. The extract physical properties measured were particle size (Malvern Mastersizer), flow (Carr's compressibility index; minimum orifice diameter), hygroscopicity (method of Callahan et al), and low-pressure compression physics (method of Heda et al). Results. The phytochemical properties differed greatly among the extracts and were extremely sensitive to changes in storage conditions, with marked instability under conditions of elevated humidity. All extracts exhibited moderate to free-flow properties and were very hygroscopic. Compression properties varied among the extracts and differed from a common use excipient, microcrystalline cellulose. Conclusions. Three commercial sources of SJW extracts exhibited different physical and chemical properties. Standardization to 1 or 2 marker compounds does not ensure chemical equivalence nor necessarily equivalent pharmacological activity. Flow and compression properties appear suitable for automatic capsule-filling machines, but hydroscopicity and the moisture sensitivity of the phytochemical profile are concerns.
PMCID: PMC2751215  PMID: 12049489
Hypericum perforatum; St John's Wort; Nutraceuticals
3.  Study of crystallization of endogenous surfactant in Eudragit NE30D-Free films and its influence on drug-release properties of controlled-release diphenhydramine HCI pellets coated with Eudragit NE30D 
AAPS PharmSci  2001;3(2):57-68.
This study investigates the crystallization of the endogenous surfactant nonoxynol 100 in Eudragit NE30D-free films during storage and the influences of nonoxynol 100 on the dissolution of diphenhydramine hydrochloric acid (HCL) pellets coated with Eudragit NE30D before and after aging at ambient conditions. Polarizing light microscopy showed that when Eudragit NE30D-free films were stored at ambient conditions, off-white, flower-shaped crystals formed and increased in the polymer film as storage time increased. Also, x-ray diffraction showed polymer crystals in the aged free film. Thermogravimetric analysis showed no evidence of combined volatile molecules with the polymer molecules, and Fourier transformed infrared spectroscopy (FTIR) data suggested the same chemical composition of the polymer before and after phase separation. Further, from normal light microscopy, the appearance of the melting droplets in the polymer film indicated that the polymer molecules did not form the crystals. After the extraction of nonoxynol 100 by water, the free film formed by the water-extracted Eudragit NE30D was found free of the crystals after aging at the same conditions. The combination of the thermogravimetric analysis, FTIR, and microscopy showed that the origin of the crystals in dry Eudragit NE30D-free films came from nonoxynol 100, and not from the polymer molecules themselves. Monitoring by differential scanning calorimeter, it was found that the rates of crystallization of nonoxynol 100 were faster when the films were stored at 30°C and 40°C than when stored at ambient conditions and 45°C. When stored at −5°C, the crystallization rate was nearly zero. As the temperature got closer to melting temperature, the crystallization rate was very low because the system was in a thermodynamically disfavored state. The rate gradually increased and finally passed through a maximum as the crystallization temperature decreased. As the temperature kept decreasing, the crystallization rate became small again and eventually stopped because the system turned into a kinetically disfavored state. Because the phase transition of nonoxynol 100 in Eudragit NE30D occurred at ambient conditions, its influence on the dissolution of diphenhydramine HCL pellets coated with Eudragit NE30D was studied. Three different levels of nonoxynol 100 were used in Eudragit NE30D dispersions to make 3 different batches of Eudragit NE30D film-coated, controlled-release diphenhydramine HCL pellets. The results showed the dissolution rate increased as the level of nonoxynol 100 increased in the coating formula. Compared to the commonly used water-soluble additive human peripheral mononuclear cell, nonoxynol 100 was more effective in enhancing the dissolution of diphenhydramine HCL from pellets coated with Eudragit NE30D. Further study showed that the phase separation of the surfactant during aging tends to stabilize or slightly increase dissolution rates at higher surfactant levels.
PMCID: PMC2779557  PMID: 11741265
Eudragit NE30D; Endogenous Surfactant; Free Film; Diphenhydramine HCL Pellets

Results 1-3 (3)