Fixed low-dose perindopril-indapamide combination in hypertensive patients with chronic renal failure.

The angiotensin converting enzyme inhibitor perindopril and the diuretic indapamide have been shown to be effective antihypertensive agents in patients with chronic renal failure. A fixed low-dose combination of these two agents has been proposed in the treatment of hypertension. We evaluated this combination in 26 patients with mild to moderate essential hypertension and mild to severe chronic renal failure that did not require dialysis. This was a multicenter, open trial consisting of a 2-week single-blind placebo washout period followed by 12 weeks of active treatment. At week 0, the patients received 2 mg perindopril/0.625 mg indapamide once a day or every other day, with the possibility of dosage adjustment to perindopril 4 mg/indapamide 1.25 mg at week 2, week 4, or week 8. A pharmacokinetic analysis using a population pharmacokinetic approach was performed at week 8. Twenty-three patients completed the 12-week study, at which time 14 patients were receiving 2 mg perindopril/0.625 mg indapamide daily, three were receiving 2 mg perindopril/0.625 mg indapamide every other day, and six perindopril 4 mg/indapamide 1.25 mg. Blood pressure readings (supine) decreased from 170.4+/-19.2 / 101.5+/-6.7 mm Hg before active treatment to 146.5+/-19.7 / 86.5+/-10.6 mm Hg at the end of treatment (P < .0001). Pharmacokinetic analysis showed that for indapamide and perindoprilat (the active metabolite of perindopril) the area under the curve (AUC24) increased with the severity of renal failure. No interaction was noted between the two drugs. Mean serum creatinine and sodium and serum potassium levels remained stable during the study. Impairment of renal function occurred in one patient and was considered unrelated to treatment. We conclude that a fixed low-dose perindopril-indapamide combination as first-line treatment has a good safety/efficacy ratio in hypertensive patients with chronic renal failure.

Application of population pharmacokinetics to the phase II development of an anti-Alzheimer's disease compound, S12024.

Steady-state concentrations of S12024, a novel compound for treatment of Alzheimer's disease, were studied to determine the pharmacokinetic parameters of S12024 in Phase IIa patients and to assess the effect of patient characteristics on those pharmacokinetics. A prospective sparse sampling strategy was used to obtain oral repeated data (n = 285) from 89 patients, which were analyzed using a one-compartment model and the NONMEM computer program. The model suggested that apparent clearance of S12024 was influenced by the study and by patient age. In the Spanish study, apparent clearance was increased by 68% and 26% for doses of 100 mg and 300 mg, respectively, and patient age decreased oral clearance by approximately 10% per decade in the patient age range (50 to 90 years). Data from only a few patients in the Spanish study were probably responsible for the observed study influence on apparent clearance of S12024, and no measured covariates could explain this effect. The model provided an excellent characterization of the observed data and it predicted correctly the plasma concentrations from an earlier Phase I trial and a subsequent Phase IIb study. The present model, built from Phase IIa data, provides a basis for examining the influence of patient covariates and the magnitude of their effects on the pharmacokinetics of S12024. The study effect is probably an artefact that will disappear by further expanding of the population model in the future.

Imidazoline-guanidinium and alpha 2-adrenergic binding sites in basolateral membranes from human kidney.

In the present study, we used [3H]idazoxan and [3H]rauwolscine to characterize the imidazoline-guanidinium receptive site (IGRS) and alpha 2-adrenoceptors in the human renal proximal tubule, respectively. In purified basolateral membranes, 11-fold enriched in Na(+)-K+ ATPase. [3H]idazoxan and [3H]rauwolscine binding was twofold higher than in homogenates ([3H]idazoxan: 87 +/- 19 vs. 45 +/- 23.3 fmol/mg protein, P less than 0.05; [3H]rauwolscine: 56.4 +/- 21.4 vs. 25.2 +/- 7.3 fmol/mg protein, P less than 0.01). In competition studies performed at saturating concentration of [3H]idazoxan (15 NM), specific binding was competed for by epinephrine and rauwolscine only by 10-15% but was completely inhibited by imidazoline and guanidinium compounds. Thus, in human renal proximal tubule. [3H]idazoxan mainly binds to an IGRS. The highest density of alpha 2-adrenoceptors in basolateral membranes and of IGRS in partially purified membrane preparations, suggests that these two binding sites have a different subcellular localization. When compared to the rabbit renal IGRS, the human [3H]idazoxan binding site displays different affinities for guanabenz, rilmenidine, clonidine, amiloride and its derivatives that persist after membrane solubilization. In contrast, the human and rabbit renal IGRS share similar regulatory properties such as the sensitivity to K+ and the insensitivity to Na+, divalent cations and 5'-guanylylimidodiphosphate (Gpp(NH)p). In conclusion, we demonstrated that, in the human renal proximal tubule, alpha 2-adrenoceptors are mainly located in basolateral membranes while IGRS appear to be associated with another cell compartment. As indicated by their common interaction with imidazoline and guanidinium derivatives and by similar regulatory properties, human and rabbit IGRS belong to the same family of membrane proteins.(ABSTRACT TRUNCATED AT 250 WORDS)