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Biomedical subjects

L S Wan

Publications and source records attributed to L S Wan.

At least 37 records · Page 2Linked to original sources
PubMed1985

Surfactant effect on the dissolution of sulfanilamide granules.

Polysorbate 80 incorporated in sulfanilamide granules was found to depress the dissolution of sulfanilamide. The largest decrease corresponded to the lowest concentration of surfactant used. Sulfanilamide granules formulated with either starch or microcrystalline cellulose also decreased the release of the drug. The effect of starch depressing sulfanilamide dissolution was greater with higher starch content in the granules. However, addition of polysorbate 80 improved the dissolution of sulfanilamide granules containing starch but not those with microcrystalline cellulose. This difference was found to be related to the ability of starch to swell and cause granule disintegration. The inclusion of polysorbate 80 in starch-containing granules produced softer and more densely packed granules which were more responsive to the swelling effect of starch.

Excipients↗
PubMed1981

Termination of very early pregnancy by vaginal suppositories-(15S)-15-methyl prostaglandin F2 alpha methyl ester.

A new approach to terminate very early pregnancy was tried on 49 healthy women who were proven to be pregnant from 31 to 47 days from their last menstrual period. All pregnancies were confirmed either by UCG or serum HCG-B subunit. (15S)-15-Methyl PGF2 alpha Methyl Ester in a suppository form was administered in two separate doses: 1.0 mg initial dose followed by 3.0 mg one hour later. Patients were kept under observation for 8 hours. Blood sampling for progesterone, HCG-B, and prostaglandin levels were assayed at 0 degree, 30', 1 degree, 4 degrees, 8 degrees and 14 days. Patients were re-examined at a two week follow-up visit. Pelvic examination and pregnancy tests were performed to confirm whether the pregnancy was successfully terminated. There were no significant changes in serums progesterone and HCG-B levels during the 8-hour observation period. Both levels declined significantly to very low levels at 14 days post-therapy, confirming the clinical impression of successful termination of pregnancy. Plasma prostaglandin levels rose as early as 30 minutes after initiation of therapy, peaked at 4 hours and declined gradually afterwards. Most side effects such as nausea, vomiting, diarrhea and cramps, although clinically manageable, were still bothersome. One patient experienced an episode of vasovagal syncope. The majority of patients required medical observation up to 6 hours. Clinical implications of this new approach of termination of very early pregnancy are discussed.

Abortion, Induced↗
PubMed1981

Pituitary response to LHRH stimulation in women on oral contraceptives: a followup dose response study.

Gonadotropic response to bolus intravenous injection of LHRH was measured in 36 women. Thirty of them were taking five different oral contraceptive preparations with six women in each category, and the remaining six served as controls. 150 micrograms LHRH was given during cycle days 20-25. Serum samples were obtained prior to the bolus injection and at 20 minute intervals for two hours. Five different oral contraceptive agents were selected to compare different progestins with same type and dose of estrogen, and different type or dose of estrogen with same type and dose of progestins. Significant suppression of LH response to LHRH stimulation ws observed in the agents containing 50 mcg of ethinyl estradiol or mestranol. No such suppression was noted in the product containing only 20 mcg of ethinyl estradiol. In comparing the different type of estrogenic or progestational components, no statistically significant differences in LH response were demonstrated. This finding suggests that it is not the individual component alone, but the combined action of estrogenic and progestational components which determines the potency of an oral contraceptive agent.

Contraceptives, Oral↗
PubMed1981

Clinical experience with Progestasert beyond one year of use.

A total of 254 women were enrolled in the study of the intrauterine progesterone system, Progestasert, and some of the subjects have been followed into the 8th year of use of the device. Clinical experience on 192 women in their 1st year of use of the device was reported in 1977. This follow-up study reports on 110 patients who had at least 2 insertions of the Progestasert for continuous use of 13 months, to a maximum of 8 insertions for continuous use of up to 86 months, for a total of 3808 months. 60% of subjects were nulliparous women who tolerated the device as well as the multiparous. The expulsion rate was low (3.5/100 women-years) noting that 82% of expulsions occurred within 2 months postinsertion or exchange of the device. A total of 7 pregnancies were observed; the pregnancy rate was 2.2/100 women-years. 2 of these 7 pregnancies were ectopic. No uterine or cervical perforations and no serious infections were observed.

Age Factors↗
PubMed1977

Viscosity and surface tension of dilute salicylic acid-cetrimide systems.

The viscosity and surface tension of systems containing small amounts of salicylic acid in aqueous solutions of cetrimide were determined. An abrupt increase in viscosity was observed, and the molar ratio of salicylic acid to certrimide at which this viscosity increase occurred was 1:2. The surface tension of these systems also increased sharply after an initial lowering. The salicylic acid concentration at which this behavior was demonstrated was almost the same as that at maximum solubility in the surfactant solution.

Cetrimonium Compounds↗
PubMed1976

Estrogen-containing oral contraceptive agents. A basis for their thrombogenicity.

The mechanism whereby estrogen-containing contraceptives facilitate thrombosis is obscure, and published data concerning their effect on antithrombin III are conflicting. Plasma samples were examined for the quantity of antithrombin III and activated factor X (Xa) inhibitory activity among 57 women receiving oral contraceptives and 48 controls. The quantity of antithrombin III in both groups was normal. In contrast, Xa inhibitory activity was significantly reduced (P less than .001) among patients taking oral contraceptives, compared to controls. Heparin sodium added to plasma from patients taking contraceptives raised Xa inhibitory activity toward or above normal without changing the quantity of antithrombin III. The effect of estrogen is not to decrease the quantity of plasma antithrombin III, but rather to diminish plasma Xa inhibitory activity, an effect that can be abolished by heparin.

Adolescent↗
PubMed1975

Effects of acids and bases on salicylic acid-cetrimide systems.

The effects of acids and bases on the viscosity of salicylic acid-cetrimide systems were investigated. A viscosity reduction was produced by the addition of acids and was independent of the degree of saturation of the cetrimide solution with salicylic acid. The incorporation of base followed by that of acid increased and decreased the viscosity, respectively. This viscosity behavior was demonstrated in undersaturated systems and was not goverened by the relative amounts of base or acid used. In oversaturated systems, only a lowering of viscosity was observed.

Acetates↗
PubMed1975

The effect of prostaglandin F2alpha on corpus luteal function in the rhesus monkey.

An experimental model was set up to show whether PGF2alpha caused luteolysis when adequate chorionic gonadotropin was administered. Four mature female rhesus monkeys were studied for two cycles each. HCG was given after ovulation until day 36. PGF2alpha was given on days 28 and 29 in one cycle, while the other served as control. In five out of the total eight cycles studied, the luteal function was maintained up to day 36. However, gradual decline of serum progesterone was noted after days 22 to 26 despite the continuous administration of hCG. Administration of PGF2alpha on days 28 and 29 did not accelerate CL regression. It was also noted that hCG in doses of 500 IU did not maintain CL function in three of four cycles when surgical stress was added.

Animals↗