Comparative acute effects of adenosine and prostacyclin in primary pulmonary hypertension

Vasodilators have been a main focus of therapy for primary pulmonary hypertension. Adenosine and prostacyclin have been shown to reduce pulmonary vascular resistance acutely in these patients. In order to compare the acute hemodynamic effects of adenosine and prostacyclin, ten patients with severe primary pulmonary hypertension, unresponsive to medical therapy, were studied. After baseline hemodynamics were obtained, an adenosine infusion, 50 to 100 ng/kg/min, was begun and titrated to the maximum tolerated dose. Hemodynamics were allowed to return to baseline, and thereafter, a prostacyclin infusion was begun at 2 ng/kg/min, and titrated to the maximum tolerated dose. Overall, adenosine (200 +/- 53 ng/kg/min) produced a 33 +/- 18% (p < 0.001) fall in pulmonary vascular resistance and a 52 +/- 25% (p < 0.001) increase in cardiac output with no effect on pulmonary or systemic arterial pressures. Prostacyclin (8 +/- 4 ng/kg/min) caused a 22 +/- 18% (p < 0.01) fall in pulmonary vascular resistance and a 25 +/- 26% (p < 0.05) increase in cardiac output with a 14 +/- 6% (p < 0.001) decrease in systemic arterial pressure, but no change in pulmonary arterial pressure. The effects of adenosine and prostacyclin on pulmonary vascular resistance were similar (r = 0.70, r2 = 0.49, p = 0.02). Adenosine and prostacyclin have similar hemodynamic effects acutely in primary pulmonary hypertension. Adenosine may be useful as a test of the potential for long-term prostacyclin therapy in patients with primary pulmonary hypertension.

Immunoreactive endothelin-1 concentrations in follicular fluid of women with and without endometriosis undergoing in vitro fertilization-embryo transfer

OBJECTIVE

To determine the concentrations of immunoreactive (IR) endothelin-1 in human follicular fluid (FF) and whether IR-endothelin-1 levels are different in women with endometriosis-associated infertility.

DESIGN

Follicular fluid and plasma samples, obtained from women with and without endometriosis undergoing IVF-ET, were collected at the time of oocyte aspiration and analyzed for IR-endothelin-1 levels.

SETTING

Infertility clinic in an academic research environment.

RESULTS

Overall, 90% of FF samples and 60% of plasma samples contained IR-endothelin-1 detectable above the threshold of assay sensitivity. Immunoreactive endothelin-1 levels (mean +/- SEM) in FF samples from women with and without endometriosis-associated infertility were 74 +/- 12 and 37 +/- 6 pg/mL, respectively. There was no difference in IR-endothelin-1 levels in FF samples between controlled ovarian hyperstimulation cycles with or without leuprolide acetate. No significant differences were detected in plasma IR-endothelin-1 levels in women with endometriosis-associated infertility when compared with those without.

CONCLUSIONS

These results demonstrate the presence of IR-endothelin-1 in human FF obtained at the time of oocyte aspiration for IVF-ET and higher levels of IR-endothelin-1 in FF of women with endometriosis-associated infertility.

Individual and combined effects of cimetidine and ciprofloxacin on theophylline metabolism in male nonsmokers

1. The individual and combined effects of cimetidine and ciprofloxacin on theophylline metabolism were examined in six young male nonsmokers. 2. Treatment sequence consisted of 7 days each of cimetidine 400 mg p.o. every 12 h. ciprofloxacin 500 mg p.o. every 12 h, and the combination of cimetidine and ciprofloxacin. 3. Studies of theophylline pharmacokinetics were performed at baseline and on the fifth day of each regimen. 4. Individually, cimetidine and ciprofloxacin decreased the clearance of theophylline by 25% and 32%, respectively. Therapy with the combined regimen resulted in a 41% reduction in theophylline clearance, which was greater than that achieved with each drug alone (P < 0.01). 5. Ciprofloxacin, in contrast to cimetidine, inhibited N-demethylations of theophylline to a significantly greater extent than the hydroxylation pathway. Combined treatment produced a further decline in formation of 1,3-dimethyluric acid than each drug alone. 6. These data suggest that coadministration of cimetidine and ciprofloxacin exerts a greater impairment of theophylline biotransformation than each inhibitor alone. The enhanced inhibitory effect from the two inhibitors will occur only when sub-maximal doses of each individual agent are used.