Kinetics of thermal degradation of betamethasone valerate and betamethasone dipropionate in different media.

The effect of pH, media, phosphate concentration and ionic strength on the kinetics of thermal degradation of betamethasone valerate and betamethasone dipropionate has been investigated. A validated HPLC method has been used to determine the parent compounds and their major thermal degradation products identified in the reaction. Betamethasone-17-valerate gave rise to two major products, namely, betamethasone-21-valerate and betamethasone alcohol, and betamethasone dipropionate degraded into three major products, namely, betamethasone-17-propionate, betamethasone-21-propionate and betamethasone alcohol, in different media. Betamethasone valerate showed maximum stability at pH 4-5 while betamethasone dipropionate was maximally stable at pH 3.5-4.5. The degradation of betamethasone valerate and betamethasone dipropionate was found to follow first-order kinetics and the apparent first-order rate constants (k(obs)) for thermal degradation in different media range from 0.399-9.07×10(-3) h(-1) and 0.239-1.87×10(-3) h(-1), respectively. The values of the rate constants decrease with increasing solvent polarity, phosphate concentration and ionic strength. The second-order rate constants (k΄) for the phosphate ion inhibited reactions lie in the range of 3.02-1.30×10(-6) M(-1) s(-1).

Cephalosporin resistance and beta-lactamase production in clinical isolates of Staphylococcus aureus in Karachi.

WHO recommends surveillance program for monitoring antibiotic resistance. The present study is a step in this direction. More than 100 clinical isolates of Staphylococcus aureus were collected from different hospitals in Karachi and in vitro studies were carried out by Agar dilution method using different generation of cephalosporins. The result showed high resistance to majority of these antibiotics with increase in the MIC's while only ceftriaxone and ceftazidime were the most potent one showing significant antimicrobial activity. For the detection of beta-lactamase iodometric method was used which showed that 80% strains produced beta-lactamase which clearly depict the misuse of these agents.

Resistance pattern of clinical isolates from cases of chronic ear infection II.

During present study hundred clinical isolates from cases of ear infection were tested from local population for resistance pattern, using eleven different antibiotics. A considerable percentage of isolates causing ear infection was resistant to number of antimicrobial drugs. The percentages of organisms isolated from ear infection are Pseudomonas aeruginosa (50%), Proteus species (16%), Staphylococcus aureus (15%), Klebsiella species (13%) and Escherichia coli (6%).

Seven-day viable analysis of some ophthalmic preparations with different concentrations of benzalkonium chloride.

The efficacy of zinc sulphate and boric acid ophthalmic preparations, containing benzalkonium chloride as preservative have been investigated against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria. The viability of bacteria was checked after 7 days though they were completely suppressed after 24 hours of inoculation. Zinc sulphate increased the antimicrobial activity of benzalkonium chloride, whereas the boric acid or its combination with zinc sulphate reduced the same. The Pseudomonas aeruginosa was found to be viable against zinc sulphate, boric acid or its combination at a concentration of 0.01% to 0.005% of the preservative. Escherichia coil and Staphylococcus aureus also exhibited resistance but to a lesser extent than Pseudomonas aeruginosa. This viability may be dangerous in case of multidose ophthalmic preparations.

Studies on the antimicrobial activity of honey.

Ten samples of crude and processed honey were used to determine antimicrobial activity against twenty five species of pathogenic and nonpathogenic bacteria, commonly encountered in human infections. The antifungal activity was checked against ten parasitic and saprophytic fungi. Most of the samples of honey used in the study showed broad spectrum antibacterial and promising antifungal activity.

Screening of marine algae of karachi for haemagglutinin activity.

Ethanol extracts of 66 species of marine benthic algae, collected from the coastal areas of Karachi, Pakistan, were tested for haemagglutination against human erythrocytes of blood groups A, B, AB and O. Out of 23, 16 and 27 species of green, brown and red seaweeds only 12,5 and 14 species respectively exhibited a positive test for the bioactivity of haemagglutinins i.e. the activity was found in half of the investigated species of Chlorophyta and Rhodophyta but only in one third of Phaeophyta.

[The effect of opiate receptor agonists on the blood circulation in rats with hemorrhagic shock]. / Vliianie agonistov opiatnykh retseptorov na krovoobrashchenie u krys s gemorragicheskim shokom.

The effect of intravenous infusion of agonists of mu-(DAGO) and delta-(DADL, DAAE) opiate receptors on mean arterial pressure and heart rate was studied in experiments on rats with dosed blood loss of up to 30% of calculated blood volume. Stimulation of mu-opiate receptors inhibited the drop of mean arterial pressure in hemorrhagic shock, whereas stimulation of delta-opiate receptors failed to produce such an effect. Preliminary injection of naloxone blocked the effects of mu-receptor stimulation.