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Biomedical subjects

J A Orwa

Publications and source records attributed to J A Orwa.

8 recordsLinked to original sources
PubMed2004

Influence of manufacturing practices on quality of pharmaceutical products manufactured in Kenya.

OBJECTIVE: To establish the quality of pharmaceutical products manufactured by the respective industries in Kenya and determine the effect of manufacturing practices on the quality of these products. DESIGN: Cross-sectional study. SETTING: Industries examined are in Nairobi, Kenya. Laboratory analysis was carried out using available facilities at Kenya Medical Research Institute and University of Nairobi, Faculty of Pharmacy. INTERVENTIONS: Structured Questionnaires were administered to examine how the code of good manufacturing practices has been used in the production of each pharmaceutical product by respective companies. Questionnaires designed to evaluate the distribution and carry out limited post-market surveillance study were administered to community pharmacy outlets. Drugs were sampled and analyzed for their quality according to the respective monographs. MAIN OUTCOME MEASURES: The questionnaires administered to the industry included the source of raw materials, quarantine procedure before and after manufacture, manufacturing procedure, quality audit, quality assurance procedure, equipment, and staff. That administered to the pharmacy outlet included availability, affordability and acceptability of locally manufactured pharmaceutical products. Quality analysis of products involved the establishment of the chemical content, dissolution profile, friability, uniformity of weight and identity. For antibiotic suspensions the stability after reconstitution was also determined. RESULTS: There were 15 respondents and two non-respondents from the industry and six out of nine respondents from the pharmacy outlets. The ratio of qualified staff to product range produced seemed to influence product quality. Industries producing several products with only limited number of pharmaceutical staff had more products failing to comply with pharmacopoeia specifications compared to those producing only few products. Nevertheless, all companies are well equipped with quality control equipment, in accordance with type of product manufactured. Private pharmacies stocked few of the locally manufactured products. The reason, they said, was due to low doctor and/or patient acceptance. Compliance with quality specifications as set out in respective monographs was overall 76%. CONCLUSION: Although the local pharmaceutical industries have adopted good manufacturing practices leading to many good quality products currently in commerce, these manufacturing practices are not comprehensive and measures need to be taken to continue improving them.

Cross-Sectional Studies↗
PubMed2002

Study of the stability of polymyxins B(1), E(1) and E(2) in aqueous solution using liquid chromatography and mass spectrometry.

Polymyxins B(1), E(1) (colistin A) and E(2) (colistin B) were subjected to degradation in aqueous solutions of different pH values (1.4, 3.4, 5.4 and 7.4) and at different temperatures (37, 50 and 60 degrees C) in order to investigate the characteristics of decomposition. The progress of decomposition was followed by reversed-phase liquid chromatography on YMC-Pack Pro, C-18 stationary phase. The degradation curves showed (pseudo) first order kinetics. The pH-rate profiles indicate that colistin is more susceptible to degradation in solutions of pH above 5 and is more stable in acidic media. The degradation of polymyxin B(1) was most rapid at pH 7.4. Qualitative analysis of the degradation products by LC/MS reveals that racemization is the major mechanism of degradation in both acidic and neutral media.

Anti-Bacterial Agents↗
PubMed2001

Isolation and structural characterization of polymyxin B components.

Polymyxin B is a peptide antibiotic complex present as sulphate. The components were separated preparatively on a poly(styrene-divinylbenzene) (PLRP-S), 1000 A, 8 microm, 250 x 12.5 mm I.D. stationary phase maintained at 60 degrees C and using 215 nm detection. Elution was carried out with acetonitrile-sodium sulphate solution (0.7%, m/v; pH adjusted to 2.5 with trifluoroacetic acid)-water (18:50:32, v/v) at a flow-rate of 4.0 ml/min. Seven polymyxin B components were isolated and characterized using 1H and 13C NMR. The molecular masses were confirmed by mass spectrometry. The structures of two components were determined for the first time. Polymyxins B5 and B6 were identified as having the same composition as polymyxin B1 except that the fatty acid moiety was nonanoic acid and 3-hydroxy-6-methyloctanoic acid, respectively.

Chromatography, Liquid↗
PubMed2001

Isolation and structural characterization of colistin components.

Preparative-scale separation of colistin sulphate bulk sample was carried out on a preparative poly(styrene-divinylbenzene) stationary phase. Isocratic elution with acetonitrile-sodium sulphate solution (0.7% m/v; pH adjusted to 2.5 with TFA) - water (16:50:34, % v/v/v) was carried out at a flow rate of 4.0 ml min(-1). Six colistin components were isolated and characterized using 1H and 13C NMR. The molecular weights were confirmed by mass spectrometry. The structures of 2 components were determined for the first time. Polymyxin E7 was identified as having the same composition as polymyxin E1, except that the fatty acid moiety was 7-methyloctanoic acid. Isoleucine polymyxin E8 was characterized as having the same composition as isoleucine polymyxin E1 with 7-methylnonanoic acid as the fatty acid moiety.

Anti-Bacterial Agents↗
PubMed2000

Analysis of polymyxin B sulfate by capillary zone electrophoresis with cyclodextrin as additive. Method development and validation.

A capillary zone electrophoresis method for analysis of polymyxin B sulfate is described. In this method, triethanolamine (TEA)-phosphate buffer at pH 2.5 was employed to reduce the adsorption of analyte onto the capillary wall. Methyl-beta-cyclodextrin (M-beta-CD) and 2-propanol (IPA) were found to be necessary for selectivity enhancement. In order to optimize the method and to control its robustness, a central composite design was performed with four parameters, i.e. concentration of M-beta-CD, TEA, IPA and buffer pH. The optimal separation conditions were as follows: capillary, 55 cm (50 microm I.D., 47 cm effective length); 130 mM TEA-phosphate buffer (pH 2.5) containing 5 mM M-beta-CD and 5% IPA; 24 kV (51 microA) applied voltage; column temperature, 20 degrees C. Further, linearity and limits of detection quantification were examined. Three commercial samples were analyzed quantitatively.

Cyclodextrins↗
PubMed2000

Liquid chromatography of polymyxin B sulphate.

A reversed-phase liquid chromatography method for analysis of polymyxin B sulphate is described. The method uses a YMC-Pack Pro, C18, 5 microm, 250x4.6 mm I.D. column maintained at 30 degrees C. The mobile phase comprises acetonitrile-sodium sulphate (0.7%, m/v)-phosphoric acid (6.8%, v/v dilution of 85%, m/m phosphoric acid)-water (22.25:50:5:22.75) at a flow-rate of 1.0 ml/min. Detection was by UV at 215 nm. The method is able to resolve polymyxin B1, the major component, from more than thirty other components present in the complex. Robustness was evaluated by performing a full-factorial design experiment. The method showed good selectivity, repeatability, linearity and sensitivity.

Anti-Bacterial Agents↗
PubMed1999

Liquid chromatography method for separation of clindamycin from related substances.

A reversed-phase liquid chromatography method has been developed for the separation of clindamycin from 7-epiclindamycin, clindamycin B, lincomycin, lincomycin B, 7-epilincomycin and other impurities of unknown identity. The method uses a Hypersil ODS, 5 microm, 250 x 4.6 mm i.d. column maintained at 45 degrees C. The mobile phase comprises acetonitrile phosphate buffer (1.35% v/v phosphoric acid, adjusted to pH 6.0 with ammonium hydroxide)-water (35:40:25, v/v) at a flow rate of 1.0 ml/min. UV detection is performed at 210 nm. The method was tested on several C-18 columns and showed good robustness. Robustness was further evaluated by performing a full-fraction factorial design experiment. The method showed good selectivity, linearity, and repeatability. It is also suitable for analysis of clindamycin formulations.

Anti-Bacterial Agents↗