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"Abuga K. O., Chepkwony H.K., Roets E., Hoogmartens J. A Stability-indicating HPLC method for the separation of clarithromycin and its related substances in bulk Samples." J. Sep. Sci.. 2001;24:849-855. AbstractWebsite

Clarithromycin is a 6-O-methylated semi-synthetic derivative of erythromycin A,
which is more resistant towards acid decomposition. Commercial clarithromycin
samples contain several potential impurities arising from the manufacturing process
and degradation. A simple, selective, and sensitive isocratic liquid chromatographic
method has been developed for the impurity profiling of clarithromycin bulk samples.
The method employs a XTerra RP18, 5 lm, 25064.6 mm column thermostated at
568C. The mobile phase consists of acetonitrile ± 0.2 M potassium phosphate buffer
pH 6.80 ± water (40 : 3.5 :56.5). Several peaks are of unknown identity. The method
is stability indicating.

"Abuga K.O., Kokwaro G.O., Bosire K.O. Concomitant administration of theophylline and oxamniquine in rats: Effect on theophylline clearance." East Cent. Afr. J. Pharm. Sci. . 1998;1(1):22-23. AbstractWebsite

This report describes an investigation into the effect of oxamniquine on systemic clearance of theophylline in rat. Male Wister rats (N=12, 5 weeks old) were divide into 3 groups (N=4 per group) and administered buffer plus theophylline (10 mg/kg), controls, oxamniquine( 5 mg/kg), and theophylline (10 mg/kg) oxamniquine (20 mg/kg) intravenously. Theophylline clearance was estimated from a single plasma sample obtained 6 hours post drug administration. Oxamniquine had no effect on theophylline clearance compared to controls. It was concluded that clinically important interaction between oxamniquine and theophylline is unlikely to occur.

"Abuga K.O., Mwagiru P.M., Thoithi G.N., Nguyo J.M., Ngugi J.K., King'ondu O.K., Mugo H.M. and Kibwage I.O. Quality of antiretroviral drugs analyzed in the Drug Analysis Research Unit during 2000-2003." East cent. Afr.J. Pharm. Sci.. 2003;6(1):20-23. AbstractWebsite

During the period 2000-2003, the Drug Analysis and Research Unit received and analyzed 33 samples of antiretroviral drugs. Locally manufactured products accounted for 57.6% of the samples, while the imported drugs constituted 42.4%. The drugs consisted of single, double and triple component preparations. They were subjected to identity, assay and dissolution tests. 30 samples (90.9%) complied with compendial specifications for these tests, while 3 failed. The results obtained show that the manufacture of quality generic antiretroviral drugs is achievable.

Okaru AO, Abuga KO, Kibwage IO, Hausler T, Luy B, Kuballa T, Rehm J, Lachenmeier DW. "Aflatoxin contamination in unrecorded beers from Kenya – A health risk beyond ethanol." Food Control. 2017;79:344-348. Abstract

Samples of unrecorded opaque beers (n=58; 40 based on maize, 5 on sorghum and 13 on other plants) and recorded wines (n=8) in Kenya were screened for aflatoxins using a rapid ELISA technique followed by confirmation using liquid chromatography-tandem mass spectrometry. Six of the maize beers were obtained from Kibera slums in Nairobi County. Aflatoxin contamination was detected in six unrecorded beers (10%), but in none of the recorded wines. Remarkably, three of the aflatoxin positive samples were from the Kibera slums.
The concentration of aflatoxins in the positive samples had a mean of 3.5 µg/L (range 1.8–6.8 µg/L), corresponding for an average consumption of 500 mL (1 standard drink) to a margin of exposure (MOE) of 36 (range: 15–58), which is considered as risk. On the other hand, the alcoholic strength of the aflatoxin positive samples had a mean of 4.3% vol (range 3.5-4.8%) corresponding to a MOE of 2.5 (range of 2.2-3.0) for the equivalent consumption volume. While aflatoxins pose a risk to the consumer, this risk is about 10 times lower than the risk of ethanol.
The Joint FAO/WHO Expert Committee on Food Additives sets no acceptable daily intake for aflatoxins since they are genotoxic carcinogens and instead recommends for the reduction of aflatoxin dietary exposure as an important public health goal, particularly in populations who consume high levels of any potentially aflatoxins contaminated food. Nevertheless, ethanol still posed a considerably higher risk in the unrecorded beers examined. However, consumers should be informed about aflatoxins, as these are an involuntary and unknown risk to them. In addition, producers should be educated about measures to reduce aflatoxins.

Abuga K, Nyamweya N. "Alcohol-Based Hand Sanitizers in COVID-19 Prevention: A Multidimensional Perspective." Pharmacy. 2021;9(1):64. Abstract

The global use of alcohol-based hand sanitizers (ABHS) as an important means of controlling the transmission of infectious disease has increased significantly as governments and public health agencies across the world advocated hand hygiene as a preventative measure during the COVID-19 pandemic. Although the performance of these products is most commonly defined as a function of their alcohol concentration, they are multifaceted products in which an interplay of several factors is important in determining efficacy. This paper discusses the interplay between ABHS input (formulation) factors and output (product performance) factors in the context of a multidimen-sional perspective using a novel representative paradigm. In the model, represented in the form of a three-dimensional tetrahedron, each of the faces represents inputs in the manufacturing of the ABHS product, which are the type and amount of alcohol, the inactive ingredients, the formulation and the manufacturing practices. The four corners of the tetrahedron represent the product per-formance factors which include product efficacy, sensory characteristics, usage and compliance and product safety. The multidimensional approach to the formulation and evaluation of ABHS shows that several factors contribute to the effectiveness and utility of these products. The paradigm provides a useful framework for manufacturers of ABHS and related healthcare products.

Babiaka SB, Simoben CV, Abuga KO, Mbah JA, Karpoormath R, Ongarora D, Mugo H, Monya E, Cho-Ngwa F, Sippl W, Loveridge JE, Ntie-Kang F. "Alkaloids with Anti-Onchocercal Activity from Voacanga africana Stapf (Apocynaceae): Identification and Molecular Modeling." Molecules. 2021;26(1):70. Abstract

A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight known compounds—voacangine (2), voacristine (3), coronaridine (4), tabernanthine (5), ibox-ygaine (6), voacamine (7), voacorine (8) and conoduramine (9)—were isolated from the stem bark of Voacanga africana. The structures of the compounds were determined by comprehensive spec-troscopic analyses. Compounds 1, 2, 3, 4, 6, 7 and 8 were found to inhibit the motility of both the microfilariae (Mf) and adult male worms of Onchocerca ochengi, in a dose-dependent manner, but were only moderately active on the adult female worms upon biochemical assessment at 30 μM drug concentrations. The IC50 values of the isolates are 2.49–5.49 µM for microfilariae and 3.45–17.87 µM for adult males. Homology modeling was used to generate a 3D model of the O. ochengi thioredoxin reductase target and docking simulation, followed by molecular dynamics and binding free energy calculations attempted to offer an explanation of the anti-onchocercal struc-ture–activity relationship (SAR) of the isolated compounds. These alkaloids are new potential leads for the development of antifilarial drugs. The results of this study validate the traditional use of V. africana in the treatment of human onchocerciasis.

Mubiu JK, Ndwigah SN, Abuga KO, Ongarora DSB. "Antimicrobial activity of extracts and phytosterols from the root bark of Lonchocarpus eriocalyx." East Cent. Afr. J. Pharm. Sci. . 2017;20:13-16. Abstract

The root bark of Lonchocarpus eriocalyx was dried, powdered and extracted using chloroform, methanol and hot water. The extracts exhibited antibacterial activity against Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus and antifungal activity against Saccharomyces cerevisiae. The decoction (100mg/ml) was more active than the chloroform and methanol extracts against the four microorganisms. Chromatographic fractionation of the chloroform extract using normal phase silica yielded the phytosterols lupeol and lupenone. At 100 mg/ml, the compounds were active against all the four microorganisms, with lupeol being more active than lupenone. This is the first report of the isolation of lupenone from Lonchocarpus eriocalyx.

Babiaka SB, Nia R, Abuga KO, Mbah JA, Nziko VN, Paper DH, Ntie-Kang F. "Antioxidant potential of flavonoid glycosides from Manniophyton fulvum Müll. (Euphorbiaceae): Identification and molecular modeling." Scientic African. 2020;8(e00423):1-7. Abstract

Chemical investigation of the leaves of Manniophyton fulvum led to the isolation of seven flavonoid glycosides: myricetin-3-O-β-Dd-rhamnoside (1), kaempferol-3-O-β-d-rhamnoside (2), quercetin-3-O-β-d-glucoside (3), quercetin-3-O-β-d-rhamnoside (4), quercetin-3-O-β-d-galactoside (5), rutin (6) and quercetin (7). The structures of the compounds were established by spectroscopic analyses as well as by comparison with published data. Some of the compounds showed strong antioxidant activity which validates the traditional use of the plant. An attempted correlation between the computed HOMO-LUMO energies and the measured antioxidant activities was established. We have also estimated the cardiotoxicity of the compounds by calculating the predicted logarithm of the human Ether-`a-go-go Related Gene (loghERG) using the QikProp program. These purified flavonoids are new potential lead compounds for the development of antioxidant drugs.

Ndwigah S, Stergachis A, Abuga K, Mugo H, Kibwage I. "Availability and Prices of Antimalarials and Staffing Levels in Health Facilities in Embu County, Kenya." East Cent. Afr. J. Pharm. Sci.. 2019;22(1):26-34. Abstract

Effective treatment of malaria relies on the availability of quality medicines while pricing is a major determinant of affordability. In addition, adequate numbers of competent staff of different cadres is essential for a well-functioning health system and effective health service delivery. The aim of the study was to determine the availability and prices of antimalarial medicines as well as staffing levels in healthcare facilities located in Embu County, Kenya. Antimalarials were sampled from 11 public (government owned) facilities, 29 private pharmacies, 5 private-for-profit and 3 not-for-profit mission health facilities in May-June 2014. The majority of public facilities (91%) had artemether-lumefantrine (AL) tablets in stock. Government and mission facilities did not stock second line antimalarials or sulfonamide-pyrimethamine (SP). All public facilities provided antimalarials free-of-charge to patients. Private pharmacies stocked a wider variety of antimalarials. The facilities studied were stocked with recommended antimalarials both in the private and public domains. No oral artemisinin monotherapies were encountered during the study. Only 45% percent of public facilities employed pharmacists. Of the remaining facilities, 27% employed pharmaceutical technologists while in the rest of the facilities pharmaceuticals were in the custody of nurses. Notably, none of the private-for-profit or mission facilities had pharmacists employed in their establishments; one facility employed a pharmaceutical technologist, while the rest were staffed by nurses. The number of private pharmacies superintended by pharmacists and pharmaceutical technologists were 7 (24%) and 22 (76%), respectively.

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