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Biomedical subjects

N H Choulis

Publications and source records attributed to N H Choulis.

At least 19 recordsLinked to original sources
PubMed1980

Consistency study of semi-solid pharmaceutical preparations.

The study of the consistency of a number of semi-solid pharmaceutical preparation, namely: simple ointment base, paraffin ointment base, emulsifying ointment base and soft paraffin (m.p. 47--49 degrees C) was conducted using an apparatus designed for the purpose in this laboratory. Factors such as temperature and shearing stress of motive force were taken into consideration. A mathematical equation was developed for the extrapolation of the results.

Elasticity↗
PubMed1978

Long acting methadone formulations.

Studies conducted in this laboratory have indicated the feasibility of producing long-acting methadone tablets. In examining further, methadone hydrochloride suspensions were developed using spermaceti or eudragit retard-1 for particle coating. These procedures involved the addition of the active compound (methandone hydrochloride) to: a) melted spermaceti which was dried, and the dried mixture was pulverized and added to a methyl cellulose water solution; afterwards wild cherry syrup was added to the suspension, and b) Eudragit retard-1 crystals which were pulverized, dissolved in acetone/isopropanol (1:1) solvent system, dried, and to this product again the suspending agent methyl cellulose was added followed by wild cherry syrup to produce suspensions containing 10, 20, and 30 mg/ml methadone. These formulations were further used for in vivo studies, in male albino rats of Wistar strain. The pain threshold method was utilized in order to determine the duration of methadone. Over 75 h resistance to pain was recorded. Using the same technique, suspensions of methadone-naloxone combinations and the salts methadone-alpha-naphthalenesulfonate and methadone-o-benzoylbenzoate were prepared and examine similarly.

Analgesics↗
PubMed1978

NMR studies of sustained release methadone tablets.

NMR studies for the identification of methadone in sustained release tablets is conducted. Up-field shifts of the N-methyl and phenyl groups of the compound were observed. These changes indicate an increased lipid solubility and therefore better absorptivity of the drug in the current form.

Delayed-Action Preparations↗
PubMed1977

Sustained release methadone salts and methadone-naloxone mixtures. Part 2: In vitro studies of methadone release.

Various tablet formulations, using two methadone salts namely methadone-alpha-naphthalenesulfonate and methadone-o-benzoylbenzoate and a number of methadone-naloxone combinations were prepared. The quantities of methadone released from these tablets in simulated gastric and intestinal fluids were examined using spectrophoto-metric studies. All formulations followed a typical release pattern, indicating a high degree of consistency of the formulations.

Delayed-Action Preparations↗
PubMed1976

Long acting methadone.

Tablets were prepared using pan-coating, congealing, plasticization with organic solvents and direct compression methods. The tablets were evaluated using the official dissolution test, and an analysis of the active ingredient was accomplished by employing gas-liquid chromatography. The formulation and dissolution characteristics of sustained release tablets, employing the matrix concept to regulate drug release, were studied. Particle size distribution of plastic material influenced the release rates from porous inert matrices, and it was found that incomplete drug release occurred from these preparations. Three-layer slowly-eroding sustained release tablets, using a swellable gum (carbomer) were formulated; by adjusting the proportion of the gum quantitative release of the drug was attained. Approximation of linearity for drug release-time relationship was achieved from three-layer slowly-eroding tablets containing different concentrations of drug in the middle and outer layers. Administration of the above tablets, containing 30 mg of methadone, produced analgesia in male albino rats for approximately 60 h, without undesirable effects.

Animals↗
PubMed1975

Timed-release tablets containing quinine sulfate.

The release rates of quinine sulfate from slowly eroding, timed-release tablets prepared with various amounts of a swellable gum, carbomer, and cellulose acetate hydrogen phthalate at different compaction pressures were attained. For the dissolution test of the prepared tablets, the method described in NF XIII was followed. The concentration of the released quinine sulfate was determined spectrophotometrically.

Delayed-Action Preparations↗
PubMed1975

Factors effecting drug release from inert matrices. Part 1: effects of surfactants on the release of quinine sulfate.

Dissolution rate studies of quinine sulfate from polyamide matrices, in simulated gastric and intestinal fluids, are carried out in the presence of hexadecyltrimethylammonium bromide, sodium lauryl sulfate and polyoxyethylene (50) stearate surfactants. The results obtained show that dissolution rate is dependent upon the pH of the disolution media and the type and concentration of surfactant. The solubilization effect of surfactants is also examined and the findings are discussed.

Chemistry, Pharmaceutical↗