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Biomedical subjects

K A Khan

Publications and source records attributed to K A Khan.

At least 19 recordsLinked to original sources
PubMed1992

Sister chromatid exchange and chromosome aberrations in mice after in vivo exposure of green S--a food colorant.

Sister chromatic exchanges (SCE) and chromosome aberrations (CA) in mice after in vivo exposure of Green S were carried out following single acute treatment. Except for the lowest dose (25 mg/kg body weight) a significant increase in the SCEs were observed in all the other doses (50, 100, and 200 mg/kg) tested. In CA study two higher doses (200 and 400 mg/kg) showed a significant increase in CA when compared with control. The minimum effective dose which induced SCE and CA was 50 and 200 mg/kg of body weight, respectively. The trend tests for the evidence of dose response effects were also significant for both SCE and CA. No significant differences were observed in cell replication kinetic (RI) analysis. A significant increase in the mitotic index (MI) was also observed in the highest dose (400 mg/kg) tested when compared with control. Thus the present study indicates that Green S can induce both SCE and CA in vivo in bone marrow cells of mice.

Animals↗
PubMed1992

Sister-chromatid exchange and chromosome aberrations induced by paracetamol in vivo in bone-marrow cells of mice.

Sister-chromatid exchange (SCE) and chromosome aberrations (CA) induced by paracetamol (PC), a common analgesic, were studied in vivo on bone-marrow cells of mice. The trend tests for the evidence of dose-response effects for both SCE and CA were significant. The significant increase in SCE as well as CA induced by PC may be attributed to the fact that PC can induce genotoxicity through DNA damage. Thus, the present study indicates that PC was genotoxic in vivo in bone-marrow cells of mice.

Acetaminophen↗
PubMed1992

Evaluation of the genotoxicity of 4-N-butylamino-1,2,3,4-tetrahydroacridine hydrochloride (centbucridine): a new local anaesthetic.

Centbucridine, a new local anaesthetic, was tested in in vivo genotoxicity assays. Three different endpoints were selected for this purpose. Chromosome aberrations (CA) and sister chromatid exchange (SCE) were analysed in bone marrow cells and DNA-strand breaks (SB) were measured in liver cells of mice following a single acute exposure. No significant differences were observed in the CA, SCE and SB studies, when compared with respective controls. An increase in the mitotic indices (MI) was observed only with the lowest dose tested in the CA study. No significant differences in the MI were observed with the two higher doses tested when compared with solvent controls. Trend tests for linear dose response were negative in all the parameters examined including MI. The overall results of the three endpoints tested indicated that centbucridine was not genotoxic in the mouse.

Anesthetics, Local↗
PubMed1991

A simple and rapid method for the quantification of Eudragit RS100 and RL100 poly(methacrylates) in sustained-release dosage forms.

A colorimetric ion-pair complexation method has been developed which provides a simple and rapid way of quantifying Eudragit RS100 and RL100 in pharmaceutical dosage forms. The quaternary ammonium groupings in these polymers appear to form an ion-pair complex with the dye tropaeolin OOO. When extracted into an organic phase, the optical density at 484 nm is linearly related to polymer concentration. Control of pH is important, and it should be maintained within the range 4.5 to 9.0. A wide range of pharmaceutical excipients commonly used in tablet, pellet, and film-coating formulations did not interfere with formation of the complex, but certain drugs were found to significantly enhance or decrease the assay response. Good reproducibility, precision, and accuracy were demonstrated when the method was applied to a film-coated pellet formulation containing an interfering drug (promethazine hydrochloride). However, removal of interfering substances must be optimized. The method was sufficiently sensitive for the determination of polymer on a single dose unit of encapsulated beads.

Acrylic Resins↗
PubMed1976

Effect of variation in compaction force on properties of six direct compression tablet formulations.

The effect of variation in compaction force on six direct compression tablet matrixes was investigated. An instrumented tablet press allowed direct measurement of applied and ejection forces. Hardness, apparent tablet density, and disintegration times also were determined. The disintegration time of spray-dried lactose tablets was essentially independent of compaction force. However, in the other systems investigated, the properties studied showed varying types of dependence on compaction pressure. A direct compression formula was developed and exhibits a decrease in disintegration time as compaction force is increased.

Chemistry, Pharmaceutical↗
PubMed1976

Effect of disintegrant type upon the relationship between compressional pressure and dissolution efficiency.

Four tablet disintegrants: a relatively insoluble sodium carboxymethyl cellulose, casein formaldehyde, calcium carboxymethyl cellulose and a cross-linked polyvinylpyrrolidone have been evaluated. Three widely used disintegrants, sodium carboxymethyl cellulose, sodium starch glycolate and a cation exchange resin were included for comparison. The effect of compressional pressure on the disintegration and dissolution behaviours of a soluble and an insoluble system containing different disintegrants were examined. The results show that disintegrant type can have a pronounced effect upon the relationship between compressional pressure and dissolution efficiency. The significance of this relationship is discussed in terms of the properties of disintegrants and the differing mechanisms by which they act.

Carboxymethylcellulose Sodium↗
PubMed1975

Disintegration properties of calcium phosphate dibasic dihydrate tablets.

The effect of compressional force on the disintegration time of tablets prepared from calcium phosphate dibasic dihydrate containing various tablet disintegrants was examined. The results show that effects of compressional force on disintegration time are of two types. The first type is that of insoluble disintegrants, e.g., starch and a cation-exchange resin, where the disintegration time initially shows a dramatic decrease. After this decrease, a further increase in compressional force appears to have no effect on the disintegration time. The second type is that of soluble disintegrants, e.g., calcium sodium alginate, sodium carboxymethylcellulose, and sodium staarch glycolate, where variation in compressional force has very little effect on the disintegration time. These results are discussed in terms of the differing mechanism whereby these substances act as disintegrants.

Alginates↗
PubMed1975

Effect of compaction on particle size.

Compressed tablets were prepared on a hydraulic press at several different compaction pressures by a standardized technique, using aspirin, dicalcium phosphate dihydrate, calcium phosphato-carbonate, alumina, and microcrystalline cellulose. All tablets except microcrystalline cellulose contained a cation-exchange resin as disintegrant. The particle-size spectra of the disintegrating compacts were evaluated using a particle-size counter or an air jet sieve. It is shown that compacts made from different materials but of the same initial particle-size spectra disintegrate to give particles of a considerably different size. Determination of the change in particle size produced by the compaction process provides useful insight into the nature of the compaction process.

Aluminum↗