Diuretic effects of a novel uricosuric antihypertensive S-8666 in rats, mice, monkeys, and dogs: Comparison with furosemide and trichlormethiazide

Diuretic activity of the aqueous extract leaves of Ficus glumosa Del. (Moraceae) in rats

Experiments were carried out to validate the use of F. glumosa extract as a diuretic in the treatment of hypertension as claimed by traditional healers. The experiments were performed under the same conditions with two synthetic pharmacological diuretics considered as check (Furosemide and Amiloride hydrochlorothiazide). The aqueous extract leaves of F. glumosa accelerated the elimination of overloaded fluid. At the maximum of diuretic response, urinary osmolarity decreased significantly when compared with controls. The single dose treatment of the aqueous extract leaves of F. glumosa has significantly increased urine volume 24 h after administration of the extract. The stability of aldosterone level, the absence of correlation with the plasma levels of sodium, and the increased clearance of free water in the animals receiving the extract show that increased diuresis and natriuresis moderate elevation are tubular in origin. The increase in Na(+), K(+), and Cl(-) induced by the extract caused alkalinization of the urine and showed a strong inhibitory effect of carbonic anhydrase and saluretic. These effects were mainly observed at the dose of 375 mg/kg. These observations confirm the traditional use in the treatment of hypertension and support the importance of the conservation of local knowledge as well as the conservation of Cameroonian biodiversity.

Enantiomer-enantiomer interaction of a uricosuric antihypertensive diuretic (DBCA) in renal tubular secretion and stereoselective inhibition by probenecid in the cynomolgus monkey

1. Enantiomer-enantiomer interaction of 5-dimethylsulphamoyl-6,7-dichloro-2,3-dihydrobenzofuran-2-carboxyl ic acid (DBCA), a uricosuric, diuretic and antihypertensive agent, was studied from the pharmacokinetics of the enantiomers following intravenous injection of individual enantiomers and racemate into male cynomolgus monkeys. Also studied was the involvement of the anion transport system in the renal excretion of DBCA by comparison of the pharmacokinetics in probenecid-treated and non-treated animals. 2. Separate administration of individual enantiomers showed higher plasma concentrations of (S)(-)-DBCA than those of the antipode, at an early period after dosing. Both enantiomers disappeared rapidly from plasma with an elimination half-life (t1/2 beta) of 0.35-0.38 h. Unbound fractions were 18.9% for the (R)(+)-enantiomer and 10.2% for the (S)(-)-enantiomer. The major portion of both enantiomers was excreted by 6 h after dosing and 77-78% of the dose was recovered within 48 h, principally as the unchanged drug. Tubular secretion contributed significantly to the renal excretion of DBCA, because tubular secretion clearance values of unbound drug (CLrf,s) were 14- to 29-fold greater than creatinine clearance. 3. The presence of the antipode decreased the tubular secretion clearance (CLrf,s) value of unbound (S)(-)-enantiomer by 30%, and tended to decrease that for the unbound (R)(+)-enantiomer, although not significantly. This indicates the occurrence of enantiomer-enantiomer interaction in the process of renal tubular secretion, and the inhibition of (S)(-)-DBCA renal excretion in the presence of the antipode. 4. Probenecid treatment significantly decreased the CLrf,s of both enantiomers, and the extent of inhibition for the (S)(-)-enantiomer (53%) was significantly higher than that for the antipode (14%). These results show that renal tubular secretion of DBCA involves an anion transport system which prefers the (S)(-)-enantiomer, and that probenecid can preferentially inhibit (S)(-)-enantiomer secretion.

High-performance liquid chromatographic method for simultaneous determination of enantiomers of 5-dimethylsulphamoyl-6,7-dichloro-2-dihydrobenzofuran-2, carboxylic acid and its N-monodemethyl metabolite in monkey plasma and urine after chiral derivatization

A quantitative method for the simultaneous high-performance liquid chromatographic (HPLC) resolution and determination of the enantiomers of 5-dimethylsulphamoyl-6,7-dichloro-2,3-dihydrobenzofuran-2-carboxyl ic acid, a new diuretic, and its N-monodemethylated metabolite in monkey plasma and urine is described. The method includes diethyl ether extraction of the samples and S-(-)-alpha-methylbenzylamide derivatization of the extract, followed by reversed-phase solid-phase extraction and injection of the resulting diastereoisomers onto a reversed-phase HPLC column. Baseline separation was obtained. The assay showed linearity over the range 0.1-50 micrograms/ml of plasma and 0.25-500 microliters of urine, with a lower limit of detection of ca. 0.01 micrograms/ml for each of the enantiomers. The method is adequate for pharmacokinetic and enantioselective disposition studies of both the diuretic and its metabolite.