Pharmacokinetics and Pharmacodynamics of Intravenous Azosemide in Mutant Nagase Analbuminemic Rats

Abstract

ABSTRACT:This paper reports 1) the increase in expression of CYP1A2 in mutant Nagase analbuminemic rats (NARs), 2) the role of globulin binding of azosemide in circulating blood in its urinary excretion and hence its diuretic effects in NARs, and 3) the significantly faster renal (CL R ) and nonrenal (CL NR ) clearances of azosemide in NARs. Azosemide (mainly metabolized via CYP1A2 in rats), 10 mg/kg, was intravenously administered to control rats and NARs. Northern and Western blot analyses revealed that the expression of CYP1A2 increased ϳ3.5-fold in NARs as compared with control. The plasma protein binding of azosemide in control rats and NARs was 97.9 and 84.6%, respectively. In NARs, plasma protein binding (84.6%) was due to binding to ␣-(82.6%) and ␤-(68.9%) globulins. In NARs, the amount of unchanged azosemide excreted in 8-h urine was significantly greater (37.7 versus 21.0% of intravenous dose) than that in control rats due to an increase in intrinsic renal active secretion of azosemide. Accordingly, the 8-h urine output was significantly greater in NARs. The area under the plasma concentration-time curve of azosemide was significantly smaller (505 versus 2790 g ⅐ min/ml) in NARs because of markedly faster CL R (7.36 versus 0.772 ml/min/kg, secondary to a significant increase in urinary excretion of azosemide and intrinsic renal active secretion). Additionally, CL NR was significantly faster (12.4 versus 3.05 ml/min/kg, because of ϳ3.5 fold increase in CYP1A2) in NARs compared with control. Based on in vitro hepatic microsomal studies, the intrinsic M1 [a metabolite of azosemide; 5-(2-amino-4-chloro-5-sulfamoylphenyl)-tetrazole] formation clearance was significantly faster (67.0% increase) in NARs than that in control rats, and this supports significantly faster CL NR in NARs. Renal sensitivity to azosemide was significantly greater in NARs than in control rats with respect to 8-h urine output (385 versus 221 ml/kg) and 8-h urinary excretions of sodium, potassium, and chloride. This study supports that in NARs, binding of azosemide to ␣-and ␤-globulins in circulating blood play an important role in its diuretic effects.Azosemide 1 [5-(4-chloro-5-sulfamoyl-2-thenylaminophenyl)-tetrazole] is a sulfonamide loop diuretic closely resembling furosemide in its diuretic action (Krück et al., 1978). Its main sites of action are both the cortical and medullary segments of the thick ascending limb of loop of Henle (Brater, 1979) where it inhibits water and solute reabsorption. It is used clinically in the treatment of edematous states and arterial hypertension; specific indications are cardiac and renal edema and ascites (Michel, 1992). Eleven metabolites of azosemide were found in rat urine and bile (Asano et al., 1984), but the diuretic effect of the drug does not require metabolism to an active metabolite (Greven, 1991).After i.v. administration of furosemide to mutant Nagase analbuminemic rats (NARs), an animal model for human familial analbuminemia, the diuretic effects of the drug (urine output and urinary e...

Role of Plasma Proteins in Pharmacokinetics of Micafungin, an Antifungal Antibiotic, in Analbuminemic Rats

“…It is reported elsewhere that globulins play an important role in the protein binding of azosemide and bumetanide in rats (7,8). Considering that the concentration of HDL in plasma of analbuminemic rats is twofold higher than that in SD rats, it is reasonable that the plasma protein binding of micafungin in analbuminemic rats is fairly high.…”

“…It is reported elsewhere that the expression of hepatic CYP1A2 increases in analbuminemic rats whereas the expression of CYP2E1 and CYP3A2 is unchanged (8). Considering that micafungin is not metabolized by such CYP isozymes (4,5,11,(14)(15)(16), it is likely that the metabolism of micafungin is not altered in analbuminemic rats.…”

“…Many studies regarding the pharmacokinetic characteristics of various drugs in Nagase analbuminemic rats have been published (2,3,(7)(8)(9)18). …”

Pharmacokinetics and pharmacodynamics of azosemide

“…It has been reported [18] from our laboratories that exercise training did not cause any changes in CYP1A2, CYP2E1 and CYP3A23 in rats. Therefore, it was expected that Cl nr could not be changed in rats with exercise training since azosemide was primarily metabolized via CYP1A2 in rats [68].…”

“…The diuretic effects were also demonstrated in rats with various disease states: nephritis produced by anti-rat kidney serum [13], hepatic damage induced by carbon tetrachloride [13], partial hepatectomy [13], diabetes mellitus induced by streptozotocin (DMIS) [13], hypertension (spontaneously hypertensive rats, SHRs and deoxycorticosterone acetate (DOCA)-salt-induced hypertensive rats) [13], proteinÀcalorie malnutrition (PCM) [14], diabetes mellitus induced by alloxan (DMIA) [15] and acute renal failure induced by uranyl nitrate (U-ARF) [16] or mercuric chloride [17]. In addition, the diuretic effect was seen in rats with mutant Nagase analbuminaemia (NARs, animal model for human familial analbuminaemia) [18], 4-and 8-week exercise (treadmill running) [19], and dehydration after 48 h water deprivation [20]. Furthermore, it had a tendency to inhibit vascular permeability (anti-oedemic effect) enhanced by histamine in rats due to diuresis and not due to anti-inflammatory action [21].…”