Delay of ovulation by meloxicam in healthy cycling volunteers: A placebo-controlled, double-blind, crossover study.

This study aimed to assess the effect of meloxicam on female ovulation. Twenty consented fertile females were monitored for 4 menstrual cycles: a baseline cycle, 2 treatment cycles, and a washout cycle between treatment cycles. In the first cycle visit, transvaginal ultrasound was performed, a blood sample for progesterone and meloxicam analysis was withdrawn, and volunteers were given a luteinizing hormone (LH) urine test kit and meloxicam or placebo. Volunteers started the treatment on the following day and asked to return the day the LH kit was positive to detect the dominant follicle. At subsequent visits, transvaginal ultrasound and progesterone and meloxicam levels were investigated. Compared to placebo, a 5-day delay in follicle rupture, a 55.7% increase in the mean maximum follicle diameter, and 33.5% decrease of plasma progesterone level were observed in the meloxicam-treated group. Such demonstrated meloxicam effects were reversed in participants who were randomized to meloxicam first and then placebo. Only minor side effects were reported by volunteers during the course of treatment. It is concluded that meloxicam resulted in a reversible delay of ovulation, an increase in follicular diameter, and a decrease in plasma progesterone level.

Meloxicam inhibits rabbit ovulation.

The nonsteroidal antiinflammatory, selective cyclo-oxygenase-2 (COX-2) inhibitor, meloxicam, was tested to assess its effect on rabbit ovulation. Meloxicam in different doses was administered intraperitoneally (ip) to adult female Californian rabbits at 2, 5, 8, and 24 h postcoitus with sperm-positive rabbits. Rabbits were killed on Day 10 of gestation. Meloxicam produced significant inhibition of ovulation in rabbits. This inhibition of ovulation by meloxicam was dose- and time-dependent. Ovulation in rabbits was completely inhibited by a single ip administration of meloxicam (20 mg/kg) when the drug was administered at 2 and 5 h postcoitus, whereas neither ovulation nor implantation were inhibited (pregnancy rate 75%) by the same dose administered 24 h postcoitus (approximately 14 h post ovulation). Further, ovulation was completely inhibited by 10 mg/kg of meloxicam when the drug was administered at 5 or 8 h postcoitus, but there was less inhibition of ovulation when 10 mg/kg of the drug was administered at 2 or 24 h postcoitus (pregnancy rate 25 and 80%, respectively). Corpora lutea, maternal plasma progesterone, ovary fresh weight, and maternal body weight gain were affected by meloxicam treatment. Histopathological findings observed in the ovaries of treated rabbits included microscopic dilatation of graffian follicles, particularly mature follicles. Some of the follicles were cystically dilated in addition to severe hemorrhage within the follicles which lost ova. These results show that ovulation can be inhibited in rabbits by meloxicam. Further studies are needed to assess the value of selective COX-2 inhibitors as potential nonhormonal contraceptive agents.

Effects of castor bean extract and ricin A-chain on ovulation and implantation in rabbits.

The anti-implantation and antiovulation effects of castor bean extract (CBE) and ricin A-chain (RAC) were evaluated in rabbits. Both CBE and RAC, administered intraperitoneally on days 5-9 of pregnancy, exhibited a pronounced decrease in maternal body weight gain and in death of all fetuses. A significant (p < 0.01) decrease of implantation sites resulted after rabbits were treated with RAC on the first 6 consecutive days of pregnancy. When female rabbits were treated with RAC for 10 consecutive days followed by human chorionic gonadotropin (hCG) (50 IU/kg intravenously), there was a 30% reduction in the number of corpora lutae. These data clearly indicate that CBE and RAC possess potent effects on implantation and ovulation in rabbits. The protein contents of castor bean extract, separated by polyacrylamide gel electrophoresis, revealed the presence of several protein bands, ricin toxin being a major constituent of the extract.

The bioequivalence study of folifer-Z: a new formulation of sustained-release iron and zinc.

The bioequivalence of Folifer-Z tablets, a new sustained-release iron and zinc formulation was evaluated and compared to that of Fefol-Z capsules in 30 healthy male subjects. Each subject received a single oral dose of either product according to a randomized two-way crossover design. A washout period of 1 week was allowed after each treatment. Blood samples were obtained over a 24-h period, and iron and zinc concentrations were measured. The pharmacokinetic parameters of Folifer-Z were Cmax (103 +/- 46.2 micrograms/dl), Tmax (5.93 +/- 2.94 h) and AUC0-24 h (1937 +/- 706 micrograms/dl per h), whereas the corresponding Fefol-Z values were Cmax (109 +/- 41.5 micrograms/dl), Tmax (6.64 +/- 2.54) and AUC0-24 h (1865 +/- 699 micrograms/h per dl). Analysis of variance on log-transformed data for Cmax and AUC0-24 h revealed lack of significant differences among the two formulations. The mean relative bioavailability of AUCtest/AUCreference was 1.07 (90% confidence interval range: 99-115%) and for Cmax test/Cmax reference was 0.96 (90% confidence interval range: 88-105%). Regarding the zinc results, the pharmacokinetic parameters of Folifer-Z values were Cmax (101 +/- 20.7 micrograms/dl), Tmax (4.86 +/- 1.53 h) and AUC0-24 h (1944 +/- 202 micrograms/h per dl), while the corresponding Fefol-Z values were Cmax (102 +/- 20.7), Tmax (4.93 +/- 1.51) and AUC0-24 h (1953 +/- 200). Analysis of variance on log-transformed zinc data for Cmax, Tmax and AUC0-24 h revealed lack of significant difference among the two formulations. The mean relative bioavailability of AUCtest/AUCreference was 0.98 (90% confidence interval range; 95-101%) and for Cmax test/Cmax reference was 0.92 (90% confidence interval range: 89-96%). The results also indicate a possible inhibition of zinc absorption by iron content of both formulations. It is concluded that Folifer-Z product is bioequivalent to Fefol-Z product.

Effect of multiple doses of rifampin on the [14C N-methyl] erythromycin breath test in healthy male volunteers.

The erythromycin breath test (EBT), which measures 14CO2 produced from [14C N-methyl] erythromycin, is one of the most frequently employed measures to examine drug interactions involving cytochrome P450 3A4 (CYP3A). However, the reproducibility and reliability of this test, and the effects of drugs that alter CYP3A activity, continue to be defined. In this study, the reproducibility of the EBT was evaluated in eight healthy volunteers before and after oral administration of 600 mg of rifampin daily for 8 days. Two sequential EBT determinations performed 5 days apart before rifampin administration were highly reproducible. Rifampin induced CYP3A, reflected in a mean percent (+/- standard deviation) increase in EBT values of 86 +/- 30%. Recovery of enzyme function after discontinuation of rifampin for 17 days was manifested as a return of EBT values to preinduction levels. These results support the utility of EBT as a valid, reproducible, and reliable measure of CYP3A activity in vivo.

Toxicity of a new antismoking mouthwash 881010 in rats and rabbits.

Male and female rats and rabbits were used in this study to investigate the acute and subchronic toxicity of a new antismoking (A.S.) mouth wash (0.5% silver nitrate as the active ingredient). The LD50 values for i.p. administration in male and female rats were 35.7 and 37.2 mg/kg body weight, respectively. The corresponding values in male and female rabbits were 113 and 128 mg/kg body weight, respectively. The oral LD50 values of the mouthwash in male and female rats were 428 and 433 mg/kg body weight, respectively. The corresponding values in male and female rabbits were 1261 and 1320 mg/kg body weight, respectively. Postmortem and histopathological examination revealed congestion, edema, hemorrhage, and mucosal necrosis with brown pigment deposition in the upper gastrointestinal and respiratory tracts for the orally treated animals and ascitis, peritoneal fat necrosis, and pigment deposition in i.p. administered animals. Subchronic toxicity involved administration of low (1.5 mg/kg), intermediate (15 mg/kg), and high (150 mg/kg) doses of A.S. mouthwash by swabbing the oral cavity daily for 30 consecutive days. Body weight, hematologic observations, and histopathological examination showed no significant differences between control and treated animals, except for dark coloration in teeth and increased platelet counts in treated rats.

Hypoglycemic effects of Teucrium polium.

Teucrium polium has a folk reputation as a hypoglycemic agent. The hypoglycemic activity of an aqueous decoction of plant aerial parts was tested in normoglycemic and streptozotocin-hyperglycemic rats. Results indicate that this extract caused significant reductions in blood glucose concentration 4 h after intravenous administration and 24 h after intraperitoneal administration. This effect could be due to enhancement of peripheral metabolism of glucose rather than an increase in insulin release.

Evidence for the site of action of glycerol trinitrate and diltiazem in inhibiting vasoconstrictor responses to norepinephrine in isolated renal arteries.

The inhibitory effects of glycerol trinitrate (GTN) and diltiazem (DZ) on contractions produced by submaximal concentrations (ED 75) of norepinephrine (NE) and potassium chloride (KCl) were studied in isolated canine renal artery rings. In addition, the site of action of these compounds in blocking NE-induced contractions was determined by using zero calcium (Ca++) buffer + 2 mM EGTA (calcium-free solution). GTN was more potent than DZ in relaxing KCl-induced contractions (potential-operated calcium channels) as well as NE-induced contractions (receptor-operated calcium channels). In a Ca++-free buffer, the response to NE was reduced to approximately 20-25% of the response in normal Ca++ (1.25 mM) buffer. GTN (1 X 10(-9)-1 X 10(-4) M) produced a marked inhibition of NE-induced contractions in Ca++-free buffer, whereas DZ had no inhibitory effect even at very high concentrations (1 X 10(-4) M). Thus, GTN and DZ appear to interfere with different components of Ca++ entry through slow channels and intracellular Ca++ release. DZ primarily blocks the influx of Ca++ from the extracellular space, whereas GTN appears to act by inhibiting Ca++ movements at an intracellular site.

Comparative relaxant effects of nitroglycerin in isolated rings from various canine vascular beds.

The potency of nitroglycerin to block contractions produced by norepinephrine, serotonin and KCl, was examined in isolated large artery rings obtained from the coronary, femoral, mesenteric and renal vascular bed of the dog. Nitroglycerin was a more potent antagonist (10-10,000 fold) of contractions produced by norepinephrine in the large coronary artery than in the other three vascular beds. Similarly, nitroglycerin blocked responses to serotonin and KCl (40 mM) more effectively in the coronary vs the femoral artery. These results suggest that nitroglycerin has selectivity for the large coronary artery of the dog in blocking contractions produced by three constrictor substances that have been implicated in coronary vasospasm.