Schistosoma mansoni: effect of gossypol on infections in mice

Gossypol, a toxic drug present in cotton seed oil, was subcutaneously injected into mice infected with Schistosoma mansoni. Injections were given daily over three 15 day-periods covering, respectively, schistosomula migration through skin and lungs, parasite establishment in the mesenteric veins and the schistosome sexual maturation phase. Worms were recovered by mesenteric perfusion and eggs were counted in livers and intestines 52 days after infection. Gossypol neither influenced schistosome development nor affected parasite fecundity. Schistosome-induced splenomegaly was not altered by gossypol, but the drug further aggravated the poor health status of the mice. In contrast to the reported activity of gossypol against other parasites, a parasiticidal activity was not detectable with schistosomes.

Pharmacokinetic study of levonorgestrel used as a postcoital agent

The pharmacokinetics and pharmacodynamics of levonorgestrel (LNG) were studied in six women given 0.75 mg LNG orally for seven days during the periovulatory phase of the menstrual cycle. Steady-state concentrations of LNG were reached within three days and serum LNG concentrations at various times on day 7 were generally lower than on day 1, presumably due to a reduced serum level of SHBG. On day 7 the volume of distribution was significantly increased and Co significantly decreased and both the clearance and elimination half-life were higher on day 7 than on day 1. Half-lives varied from 5.6 to 25.1 hours. The day-to-day intra-subject variations in serum LNG concentrations ranged from 23% to 80%. Serum concentrations of pituitary and ovarian hormones suggested that ovulation was not inhibited in four of the six subjects and was delayed in the remaining two. No significant changes in serum prolactin levels were observed.

Postcoital contraception with levonorgestrel during the peri-ovulatory phase of the menstrual cycle. Task Force on Post-ovulatory Methods for Fertility Regulation

The contraceptive efficacy and side effects of postcoital levonorgestrel used repeatedly during the peri-ovulatory period of one cycle was examined in 259 women. All subjects were of proven fertility in their present union and had ovulatory cycles as assessed from pre-treatment BBT charts. The mean number of coital acts during the treatment cycle was 7.5 (SD:2.6) and the mean number of 0.75 mg levonorgestrel tablets taken during the peri-ovulatory period was 4.0 (SD:1.2). Two pregnancies, both considered to be method failures, occurred, giving a failure rate of 0.8% per treated cycle. Although the overall effect of levonorgestrel on menstrual cycle length was small and insignificant, menstrual cycle disturbances were not uncommon. Intermenstrual bleeding or spotting occurred in 8.5% of the treated cycles and 12.5% of the cycles were less than 20 or more than 35 days. Other side effects, mainly nausea, headache and dizziness, were reported by about 20% of the subjects but the apparent incidence of these complaints varied markedly between the nine participating centres from 0% to just over 50%. The data suggest that repeated postcoital use of levonorgestrel is probably not a viable approach to fertility regulation for the majority of women who have regular intercourse and wish to limit the number of their pregnancies.

Sera of Schistosoma japonicum-infected patients cross-react with diagnostic 31/32 kD proteins of S. mansoni

Schistosoma mansoni adult worm antigens were tested for cross-reactions with sera obtained from patients infected with S. japonicum. The sera consistently recognized a doublet of bands, in immunoblots, which had molecular weights of approximately 31 and 32 kilodaltons (kD). This reaction was found to be markedly reduced with sera of patients who had received chemotherapy and who had a low risk of reinfection. Sera obtained from uninfected persons or from patients infected with other parasites never reacted with the antigen doublet. Schistosoma japonicum-infected mice produced antibodies during prepatency which predominantly recognized antigens of this molecular weight range in immunoblots performed with S. mansoni or S. japonicum proteins. Sera from S. mansoni-infected patients with a high specificity for the diagnostic S. mansoni-antigen cross-reacted with a corresponding component also in S. japonicum worms. Immunofluorescence assays performed with sera of schistosomiasis japonica patients confirmed earlier results localizing the diagnostic 31/32 kD antigens in the gut of S. mansoni. These cross-reacting 31/32 kD S. mansoni protein antigens may be applied for the immunodiagnosis of schistosomiasis japonica.

Pharmacokinetics of norethisterone in humans

The pharmacokinetics of a dose of 1mg norethisterone administered with 50 micrograms ethynyloestradiol was studied in 83 subjects. The dose was rapidly absorbed and there were wide variations in the serum NET concentrations at any particular time after dosing; the concentrations at 24 h varied from 100 to 1700 pg/ml. There was a significant negative correlation between the serum NET concentration and the time after dosing in all women. There were large inter-subject variations in the pharmacokinetic parameters, the elimination half-life and bioavailability showing 3- and 5- fold variability, respectively. Mean values for the parameters were t1/2, 7.6 h; bioavailability, 53.6 ng/ml/h; C max, 4.63 ng/ml; clearance, 22.6 l/h; and Vd 2361. There were a number of statistically significant correlations between the pharmacokinetic parameters and analysis of the correlations suggested that clearance was an important determinant of the bioavailability and of C max whereas the elimination half-life was the determinant of the NET concentration at 24 h. The pharmacokinetics of NET are compared with those of ethynyloestradiol. The wide variation in pharmacokinetics is likely to be important in determining inter-subject variations in efficacy and, particularly, side-effects of oral contraceptives especially now that low-dose formulations are widely used.