Analysis of adverse drug events in patients with bipolar disorders using the Japanese Adverse Drug Event Report database.

The aim of the present study was to survey adverse drug events (ADEs) in patients with bipolar disorders and identify risk factors using the Japanese Adverse Drug Event Report (JADER) database, a spontaneous reporting system. Data on patients with bipolar disorders were extracted from the JADER database. The Medical Dictionary for Regulatory Activities (MedDRA) preferred terms (PT) and standardized MedDRA queries (SMQ) were used to define ADEs. A multiple logistic regression analysis was performed to identify risk factors for ADEs. A total of 8653 reports of 1108 types of ADEs (PT) were registered in data collected on 3521 patients with bipolar disorders. Rash (PT) was the most frequently reported in 549 patients, followed by drug eruption (PT) in 387, fever (PT) in 364, toxicity to various agents (PT) in 291, and Stevens-Johnson syndrome (PT) in 261. Among 24 ADEs (PT) that were reported in more than 50 patients, lamotrigine was associated with increased risks of 13 ADEs (PT), followed by carbamazepine with increased risks of 8 ADEs (PT). The majority of these ADEs belonged to hypersensitivity (SMQ) or hepatic disorder (SMQ). Lithium carbonate was associated with increased risks of rash (PT), drug interaction (PT), and tubulointerstitial diseases (SMQ). All antipsychotics increased the adjusted odds ratio for neuroleptic malignant syndrome (PT). The risk of hyperglycemia/new onset diabetes mellitus (SMQ) was increased by olanzapine, quetiapine fumarate, and risperidone. We are presenting the profiles of ADEs in patients with bipolar disorders using the JADER database, and propose risk factors for 19 ADEs (PT) and 4 ADEs (SMQ).

Analysis of sex difference in the tubular reabsorption of lithium in rats.

Lithium is used in the treatment of bipolar disorder. We previously demonstrated that two types of transporters mediate the tubular reabsorption of lithium in rats, and suggested that sodium-dependent phosphate transporters play a role in lithium reabsorption with high affinity. In the present study, we examined sex differences in lithium reabsorption in rats. When lithium chloride was infused at 60 µg/min, creatinine clearance and the renal clearance of lithium were lower, and the plasma concentration of lithium was higher in female rats. These values reflected the higher fractional reabsorption of lithium in female rats. In rats infused with lithium chloride at 6 µg/min, the pharmacokinetic parameters of lithium examined were all similar in both sexes. The fractional reabsorption of lithium was decreased by foscarnet, a representative inhibitor of sodium-dependent phosphate transporters, in male and female rats when lithium chloride was infused at the low rate. Among the candidate transporters mediating lithium reabsorption examined herein, the mRNA expression of only PiT2, a sodium-dependent phosphate transporter, exhibited sexual dimorphism. The present results demonstrated sex differences in the tubular reabsorption of lithium with low affinity in rats.

Potent Inhibition of Biphasic Tubular Reabsorption of Lithium by Acetazolamide and Foscarnet in Rats.

Lithium is mainly excreted into urine, and a large fraction of lithium filtered through glomeruli is reabsorbed in the proximal tubule. However, the mechanisms responsible for lithium reabsorption remain unclear. We previously reported that the reabsorption of lithium was biphasic in rats, and that foscarnet inhibited lithium reabsorption with a high affinity type. We herein evaluated the effects of acetazolamide and foscarnet on the renal excretion of lithium in rats treated with lithium chloride at 2 doses. In rats intravenously injected with a bolus of 25 mg/kg lithium chloride, acetazolamide facilitated the urinary excretion of lithium, and increased the fractional excretion of lithium from 0.446 to 0.953, near the theoretically maximum value. At a dose of 2.5 mg/kg lithium chloride, the fractional excretion of lithium was 0.241 in control rats, 0.420 in rats administered acetazolamide, and 0.976 in rats administered acetazolamide and foscarnet. These results showed the potent inhibition of lithium reabsorption by acetazolamide and foscarnet in rats. And, it was exhibited that the effects of acetazolamide on lithium reabsorption differed with the dosages of lithium administered.

Effect of acetazolamide on lithium reabsorption and lithium-induced GSK3ß phosphorylation in rat kidney.

Lithium promotes the phosphorylation of glycogen synthase kinase-3ß (GSK3ß), and this reaction protects against acute kidney injury mediated by renal apoptosis. Lithium is considered to be reabsorbed by sodium-phosphate cotransporters and sodium-proton exchanger NHE3. This study evaluated the relation between the lithium reabsorption and the phosphorylation of GSK3ß, by using acetazolamide, an NHE3 inhibitor. In rats infused with lithium chloride, the plasma concentration of lithium was 4.77 mEq/l, and the renal clearance of lithium and its fractional excretion were calculated to be 2.29 ml/min/kg and 0.405, respectively. Coadministration of acetazolamide decreased creatinine clearance and the reabsorption rate of lithium, increased the fractional excretion of lithium, and did not affect its plasma concentration. Western blot analysis exhibited the facilitation of GSK3ß phosphorylation in the kidney cortex by lithium infusion, and acetazolamide inhibited the lithium-induced phosphorylation of GSK3ß. Lithium did not affect GSK3ß phosphorylation in the liver and did not affect Akt in the kidney cortex and liver. These data show that lithium reabsorption contributes to GSK3ß phosphorylation in the kidney cortex.

Interaction between methotrexate and nonsteroidal anti-inflammatory drugs in organic anion transporter.

The antifolate drug methotrexate is mainly eliminated from the body by renal tubular secretion via organic anion transporters. In clinical situations, severe methotrexate toxicity, due to an increase in serum concentrations, was observed after coadministration with nonsteroidal anti-inflammatory drugs (NSAIDs) or probenecid. In this study, we examined the effects of NSAIDs and probenecid on methotrexate transport via the rat renal organic anion transporter rOAT1, using Xenopus laevis oocytes. [3H]Methotrexate uptake was markedly stimulated in the rOAT1 cRNA-injected oocytes, and this uptake was inhibited by probenecid and various NSAIDs, whereas the influence of salicylate was less. The Dixon plots showed that probenecid, indomethacin and salicylate competitively inhibited rOAT1 with apparent K(i) values of 15.8 microM, 4.2 microM and 1.0 mM, respectively. These findings demonstrate that rOAT1 is the major site of the transporter-mediated interaction between methotrexate and NSAIDs and/or probenecid, leading to a decrease in renal excretion of methotrexate.

Interaction and transport of thiazide diuretics, loop diuretics, and acetazolamide via rat renal organic anion transporter rOAT1.

The renal tubular secretion of thiazides and loop diuretics via the organic anion transport system in renal tubules is required for them to reach their principal sites of action. Similarly, acetazolamide, a diuretic clinically administered for glaucoma, is excreted from the kidney by glomerular filtration and tubular secretion. In this study, we investigated the interaction and transport of these diuretics via the rat renal organic anion transporter rOAT1 by using Xenopus laevis oocyte expression system. p-[(14)C]Aminohippurate (PAH) uptake by rOAT1-expressing oocytes was inhibited in the presence of a thiazide (chlorothiazide, cyclothiazide, hydrochlorothiazide), a loop diuretic (bumetanide, ethacrynic acid, furosemide), or a carbonic anhydrase inhibitor (acetazolamide, ethoxzolamide, methazolamide). Dixon plot analysis demonstrated that the inhibition constant (K(i)) value was 1.1 mM for acetazolamide, 150 microM for hydrochlorothiazide, 9.5 microM for furosemide, and 5. 5 microM for bumetanide. Kinetic analysis revealed that acetazolamide inhibited rOAT1 competitively and that inhibition style of furosemide was a mixture of competitive and noncompetitive. [(14)C]PAH efflux was significantly enhanced when the rOAT1-expressing oocytes were incubated in the presence of unlabeled PAH, alpha-ketoglutarate, acetazolamide, chlorothiazide, or hydrochlorothiazide. rOAT1 stimulated acetazolamide uptake, which was inhibited by probenecid. Although the loop diuretics had little trans-stimulation effect on [(14)C]PAH efflux via rOAT1, the rOAT1-mediated furosemide uptake was observed. These findings suggest that rOAT1 contributes, at least in part, to the renal tubular secretion of acetazolamide, thiazides, and loop diuretics.

Inhibitory effect of anti-diabetic agents on rat organic anion transporter rOAT1.

The interactions of sulfonylureas and a novel anti-diabetic drug, nateglinide, with rat renal organic anion transporter (rOAT1) expressed in Xenopus laevis oocytes were studied. Uptake of p-aminohippurate via rOAT1 was markedly inhibited by glibenclamide and nateglinide, and moderately by chlorpropamide and tolbutamide. The inhibition constant values (K(i)) for chlorpropamide, glibenclamide, tolbutamide and nateglinide were 39.5, 1.6, 55.5 and 9.2 microM, respectively. Kinetic analysis showed that the inhibition of p-aminohippurate uptake by glibenclamide was competitive. Sulfonylureas examined and nateglinide did not show a trans-stimulation effect on [14C]p-aminohippurate efflux from rOAT1-expressing oocytes. There was no stimulation of [3H]glibenclamide uptake via rOAT1. These findings suggested that sulfonylureas and nateglinide interact with rOAT1, but these drugs are not translocated via the transporter.

Functional characterization of the rat multispecific organic anion transporter OAT1 mediating basolateral uptake of anionic drugs in the kidney.

The functional characteristics of rat organic anion transporter OAT1 were investigated using Xenopus laevis oocytes. Uptake of p-aminohippurate (PAH) by the oocytes expressing OAT1 was markedly inhibited by glutarate, alpha-ketoglutarate and probenecid, moderately inhibited by folate and methotrexate, but not inhibited by taurocholate or tetraethylammonium. Methotrexate and folate were transported by OAT1, but probenecid, a typical inhibitor of organic anion transporter, was not transported. Inhibition of PAH uptake by aliphatic dicarboxylates with various alkyl chain lengths was maximal at 5 (glutarate) and 6 (adipate) carbon atoms. OAT1-mediated PAH uptake was markedly inhibited by phorbol 12-myristate 13-acetate (PMA), phorbol 12,13-dibutyrate and mezerein, but not by 4alpha-phorbol 12,13-didecanoate. The inhibitory effect of PMA was attenuated in the presence of staurosporine, suggesting that OAT1 is regulated by protein kinase C. These results suggest that the substrate recognition of OAT1 is comparable to that of renal basolateral organic anion transporter, and the transport activity is regulated by protein kinase C.

Genetic polymorphism of the CYP2C subfamily and its effect on the pharmacokinetics of phenytoin in Japanese patients with epilepsy.

OBJECTIVE: To examine the genetic polymorphism of CYP2C9 and CYP2C19 and its effect on the pharmacokinetics of phenytoin among 44 Japanese patients with epilepsy. METHODS: Polymerase chain reaction tests with leukocyte deoxyribonucleic acid were used to detect the mutations for the amino acid substitution (Arg144-->Cys and Ile359-->Leu) in CgammaP2C9 and for the defective allele (m1 and m2) in CgammaP2C19. The pharmacokinetic parameters of phenytoin in individual patients were estimated by means of empirical bayesian analysis, in which the prior information was the population parameters for Japanese patients with epilepsy. RESULTS: Of the 44 patients, none had the CgammaP2C9 mutation for the Cys144 allele, whereas six patients were heterozygous for the wild-type (wt) and Leu359 allele (wt/Leu359) in cgammaP2C9. The maximal elimination rate (Vmax) of phenytoin among patients with heterozygous wt/Leu359 in CgammaP2C9 was 33% lower than that among patients with normal CgammaP2C9. A total of 21 patients were heterozygous for the CgammaP2C19 mutation (wt/m1 or wt/m2), and five patients had the homozygous or heterozygous mutations in CgammaP2C19 (m1/m1 or m1/m2). The Vmax values of phenytoin were slightly decreased (up to 14%) among patients with CgammaP2C19 mutations compared with patients with normal CgammaP2C19. CONCLUSION: The findings indicated that the genetic polymorphisms of CYP2C isozymes play an important role in the pharmacokinetic variability of phenytoin and that the mutation in CYP2C9 proteins (Ile359-->Leu) is a determinant of impaired metabolism of the drug among Japanese persons.