Munir N. Gharaibeh

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.

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first cycle visit, transvaginal ultrasound was performed, a blood sample for progesterone and meloxicam analysis was withdrawn, and volunteers were given a luteinizing hormone (LH) urine test kit and meloxicam or placebo.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.

Epinephrine and the Metabolic Syndrome

Epinephrine is the prototypical stress hormone. Its stimulation of all α and β adrenergic receptors elicits short-term systolic hypertension, hyperglycemia, and other aspects of the metabolic syndrome. Acute epinephrine infusion increases cardiac output and induces insulin resistance, but removal of the adrenal medulla has no consistent effect on blood pressure. Epinephrine is the most effective endogenous agonist at the β2 receptor. Transgenic mice that cannot make epinephrine and mice that lack the β2 receptor become hypertensive during exercise, presumably owing to the absence of β2-mediated vasodilatation. Epinephrine-deficient mice also have cardiac remodeling and poor cardiac responses to stress, but do not develop resting hypertension. Mice that cannot make epinephrine have a normal metabolism on a regular 14% fat diet but become hyperglycemic and insulin resistant when they eat a high fat diet. Vigorous exercise prevents diabetes in young mice and humans that overeat. However, exercise is a less effective treatment in older type 2 human diabetics and had no effect on glucose or insulin responses in older, diabetic mice. Sensitivity of the β2 receptor falls sharply with advancing age, and adrenal epinephrine release also decreases. However, treatment of older diabetic mice with a β2 adrenergic agonist improved insulin sensitivity, indicating that β2 subsensitivity can be overcome pharmacologically. Recent studies show that over the long term, epinephrine prevents hypertension during stress and improves glucose tolerance. The hyperglycemic influence of epinephrine is short-lived. Chronic administration of epinephrine and other β2 agonists improves cellular glucose uptake and metabolism. Overall, epinephrine counteracts the metabolic syndrome.

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.

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.

The Calcium Antagonistic Effect of the Volatile Oil of Teucrium polium

AbstractThe effect of the volatile oil of Teucrium polium was investigated in vitro using isolated segments of rabbit intestine. The volatile oil was found to inhibit the spontaneous movements of the intestine and the contractions of the intestine induced by depolarization with high potassium (K+) solution. Also, the volatile oil was found to inhibit 45Ca influx in the intestine in a dose dependent manner. Our results suggest that the volatile oil inhibits Ca2+ influx through the potential dependent Ca2+ channels.

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.

Effects of Ecballium elatrium Juice on Serum Bilirubin Concentration in Male Rats

AbstractThe effect of Ecballium elatrium juice on serum bilirubin concentration was examined in male rats. Jaundice was induced surgically by ligating the main bile duct. Intravenous administration of 0.05 ml of the juice two days after ligation resulted in a significant decrease in bilirubin concentration 24 h following the injection, while 0.1 ml produced a more pronounced decrease in bilirubin concentration 2.4, and 24 h after the injection. Intranasal administration of 0.1 ml of the juice also produced a significant decrease in bilirubin concentration and two doses produced more marked decrease.

A bioequivalence study of two brands of doxycycline capsules

Abstract Bioequivalence of two preparations of doxycycline (Doxydar ™ 100-mg capsules and Vibramycin ™ 100-mg capsules) were compared in a two-way crossover study. Pharmacokinetic parameters were determined for both formulations, including area under the concentration-time curve, mean maximum plasma concentration, time to maximum concentration, half-life, and the terminal rate of elimination. Statistical analysis revealed that differences between the two formulations were not statistically significant. Quality control data, including assay and disintegration, indicated that both products met the in-house specifications. It is concluded that Doxydar 100 mg is bioequivalent to Vibramycin 100 mg.

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.