Pharmacokinetics of nocloprost in human volunteers and its relation to dose.

The pharmacokinetics and absolute bioavailability of nocloprost, a synthetic PGE2-analogue with cytoprotective properties, was investigated in human volunteers as a function of the dose. Ten young male volunteers received nocloprost 5 micrograms i.v. and 100, 200 and 400 micrograms p.o. in random order at weekly intervals. Serum nocloprost levels were monitored for up to 12 h after each dose, using a specific, validated assay. After nocloprost 5 micrograms i.v. the highest serum level of 373 pg.ml-1 was found in the first sample 5 min after injection, and the subsequent decline showed one or two phases, with half-lives of 4 and 49 min. The AUC was 89 pg.h.ml-1, the total plasma clearance was 13.2 ml.min-1.kg-1, and the volume of distribution at steady state was 0.16 l.kg-1. After oral administration the maximum serum level and AUC increased in proportion to the dose. tmax showed a wide scatter, with an average value of about 30 min independent of the dose. Although not detectable in every subject, post maximum serum levels declined biphasically, with half-lives of ca 10 and 35-40 min. The absolute bioavailability after oral administration averaged about 2% and was independent of the dose.

Comparison of serum ethinyl estradiol, sex-hormone-binding globulin, corticoid-binding globulin and cortisol levels in women using two low-dose combined oral contraceptives.

The study included 69 women taking a desogestrel (n = 30)- or gestodene (n = 39)-containing low-dose combined oral contraceptive for at least 3 months. Group size was calculated to detect a difference in mean values of 80% of 1 standard deviation (alpha = 0.05, beta = 0.1). Seven serum samples were obtained up to 4 h, and 1 sample 24 h, after drug intake on 1 day between the 10th and the 21st day of the cycle. The concentrations of sex-hormone-binding globulin (SHBG), corticoid-binding globulin (CBG) and cortisol were measured in a 0- to 4-hour serum pool by radioimmunoassay. Ethinyl estradiol (EE2) levels were analyzed in single and pooled samples using anti-EE2-6 beta-carboxymethyloxime-bovine serum albumin antiserum. The area under the curves (AUC) up to 4 and 24 h and Cmax and tmax were evaluated. Statistical analysis (analysis of covariance) did not reveal a dependence of values on duration of treatment or day of cycle. Both treatments resulted in almost identical values for all parameters evaluated. The mean levels of SHBG, CBG and cortisol were in the range of 186-226 nmol/l, 89-93 mg/l and 280-281 micrograms/l, respectively. Mean maximum EE2 levels of 106-129 pg/ml were found 1.6-1.8 h after pill intake and AUC0-4 h accounted for 329-374 pg.h.ml-1. The recently reported differences in serum EE2 and CBG levels between two groups of 11 women each treated with desogestrel- and gestodene-containing pills, respectively, could not be confirmed.

Fluocortolone: pharmacokinetics and effect on ACTH and cortisol secretion during daily and alternate-day administration.

The pharmacokinetics of fluocortolone and its effect on the circadian rhythm of plasma cortisol and ACTH have been studied during different schedules of oral administration. Groups of 6 healthy male adults were given a single daily dose of fluocortolone 5, 10 and 20 mg, and another group received 20 mg every second day. Administration to all groups was continued for 8 days. Pharmacokinetic parameters of fluocortolone (half lives of absorption-t1/2a and elimination t1/2e, volume of distribution V and oral clearance (CL/f) were independent of the duration of treatment and dose. Areas under the plasma level curves, AUC and Cmax values increased in proportion to the dose, indicating dose linearity of fluocortolone pharmacokinetics. A normal morning cortisol peak occurred during all treatment schedules, which indicates that circadian cortisol secretion was not seriously affected by the glucocorticoid treatment. On the other hand, when the level of circulating fluocortolone was high the 12.00 a.m. and 4.00 p.m. cortisol levels were diminished compared to the pre and posttreatment values. There was no definite correlation between the ACTH and cortisol levels, either on treatment or on control days. ACTH levels were suppressed by daily treatment with the 20 mg dose. Thus, even during administration of a high dose of a glucocorticoid, the circadian secretion of cortisol can be preserved if the treatment is adjusted according to the half-life of the drug.