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Biomedical subjects

R M Pearson

Publications and source records attributed to R M Pearson.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effect of D-propranolol on growth and motility of flagellate protozoa.

Propranolol inhibits sperm motility and has been considered as a spermicide contraceptive. In view of the inhibitory effects of D-propranolol on sperm flagellar activity, we have investigated its effect on motility and growth of two human flagellate, protozoan parasites. D-propranolol had a dose-dependant inhibitory effect on motility of Giardia lamblia and Trichomonas vaginalis with ED50s of 0.38 and 0.66 mmol/l respectively, D-propranolol also inhibited growth of both parasites with ED50s of 0.18 and 0.23 mmol/l for Giardia and Trichomonas respectively. D-propranolol, unlike DL-propranolol is devoid of the unwanted effects of beta-blockade, and thus may be a useful antiprotozoal drug particularly after vaginal placement when it is concentrated in vaginal mucus.

Animals↗
PubMed1987

A modified trans-membrane migration method for measuring the effect of drugs on sperm motility.

1. The trans-membrane migration ratio (TMMR) technique is a simple method for quantitating and comparing the effect of drugs on sperm motility. 2. The ultrafilter membrane (Nucleopore) used allows mixing between the solutions on either side resulting in 21-fold dilution of a drug initially mixed with semen. 3. The concentration of drug originally mixed with semen does not remain constant over the incubation time. 4. The phosphate buffer saline (PBS) in the lower chamber should be replaced by PBS containing the same concentration of drug as in the upper chamber so that a homogenous system is established throughout the incubation. 5. Reports of previous studies using this technique may have underestimated the effect of drugs on sperm motility.

Biological Transport↗
PubMed1986

Comparison of the potency of d-propranolol, chlorhexidine and nonoxynol-9 in the Sander-Cramer test.

The potency of two new candidate spermicides, d-propranolol and chlorhexidine, was compared with an established agent nonoxynol-9 by the Sander-Cramer test. The lowest concentrations of nonoxynol-9, d-propranolol and chlorhexidine which consistently inhibited progressive forward sperm motility within twenty seconds were found to be 0.12, 0.44, and 4.81 mg/ml, respectively. These relative potencies and other properties of d-propranolol and chlorhexidine indicate that they should be further investigated as alternatives to nonoxynol-9 in spermicidal preparations.

Chlorhexidine↗
PubMed1986

In-vitro techniques: can they replace animal testing?

In-vitro tests for the long-term safety evaluation of drugs offer certain advantages. Specific properties of drugs can be identified including mutagenic and carcinogenic effects. The mechanisms leading to toxicity can be assessed. Tissue from several species, including man, can be examined. These tests should reduce the number of animal tests required for screening new drugs.

Animal Testing Alternatives↗
PubMed1985

Concentration of D-propranolol in cervico-vaginal mucus: targeting of a novel spermicide.

It may be possible to develop new contraceptives that can be administered by mouth and will exert their effects after concentration in cervico-vaginal mucus. D-Propranolol was administered in 80 mg doses by mouth to six healthy female volunteers. Samples of blood plasma and cervico-vaginal mucus were obtained before and on six occasions up to 24 hours after drug ingestion. D-Propranolol was concentrated in cervico-vaginal mucus. No changes in blood pressure, pulse, or forced expiratory peak flow (FEPF) were observed.

Adult↗
PubMed1985

A comparison of the effects of nonoxynol-9 and chlorhexidine on sperm motility.

The effects of Nonoxynol-9 and chlorhexidine on sperm motility were compared using the objective Transmembrane Migration Ratio method. These agents were found to be of similar potency in inhibiting sperm motility. The concentrations which reduced sperm motility by 50% (EC50) were 0.205 mg/ml for Nonoxynol-9 and 0.215 mg/ml for chlorhexidine. The implications of these findings in relation to the comparison of the effects of drugs on sperm motility and the development of new contraceptive agents are discussed.

Chlorhexidine↗
PubMed1984

Propranolol concentrations in blood serum, seminal plasma and saliva in man after a single oral dose.

A single dose of 80 mg racemic propranolol hydrochloride was administered by mouth to six healthy male volunteers. The mean concentration achieved in seminal plasma at 2 h after dosing was almost identical to that in blood serum. The concentrations of propranolol in seminal plasma and saliva were much less than those known to reduce sperm motility by 50% in vitro. The concentrations in saliva did not reflect those in blood serum. Propranolol in the dose administered in this study is unlikely to affect fertility by its presence in saliva or semen.

Administration, Oral↗
PubMed1983

Propranolol concentrations in plasma after insertion into the vagina.

Six healthy women participated in a study of the concentrations of propranolol achieved in plasma after insertion of the drug into the vagina. In four of the women the concentrations were also determined after administration by mouth. The area under the concentration curve for propranolol administered per vaginam was significantly greater than that after oral administration. There were small significant reduction in systolic blood pressure, pulse rate, and forced expiratory volume in one second after vaginal administration but these did not cause any symptomatic side effects. The tolerability of the vagina to drugs and the safety of this form of treatment remain to be determined. Probably further studies of the contraceptive effects of propranolol should be conducted with the dextro isomer of the drug.

Administration, Oral↗