• Biomolecules & Therapeutics
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• v.15 no.1
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• pp.40-45
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• 2007

The vascular relaxant effects on isolated rat aorta of amlodipine camsylates (S-, R-enantiomer, and R/S-racemate), were evaluated and compared with that of S-amlodipine besylate. Furthermore, antihypertensive effects were measured in spontaneously hypertensive rat (SHR). The S-amlodipine camsylate concentration-dependently inhibited $Ca^{2+}$-induced contraction of rat aorta with a very slow onset of action (reached its maximum at 3.5h; $ED_{50}:\;1.50\;{\pm}\;0.24$ nM), having a potency 2-fold higher than those of R/S-amlodipine camsylate $(ED_{50}:\;3.36\;{\pm}\;0.91\;nM)$ and similar to those of S-amlodipine besylate $(ED_{50}:\;1.44\;{\pm}\;0.14\;nM)$, whereas the R-amlodipine camsylate has 590-fold lower vasorelaxant activity $(ED_{50}:\;886.4\;{\pm}\;49.7\;nM)$. In SHR, orally administered S-amlodipine camsylate produced a dose-dependent and long-lasting (>>10 h) antihypertensive effect $(ED_{20}:\;0.89\;mg/kg)$, with a potency 2-fold higher than those of R/S-amlodipine camsylate $(ED_{20}:\;1.82\;mg/kg)$ and similar to those of S-amlodipine besylate $(ED_{20}:\;0.71\;mg/kg)$. In contrast, the R-amlodipine camsylate has no effect even-though administrated high concentration 10 mg/kg. These results suggest that S-amlodipine camsylate has the potency and long-lasting antihypertensive activity as single enantiomer drug, and its antihypertensive effect is not significantly different to that of S-amlodipine besylate.

• Biomolecules & Therapeutics
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• v.11 no.2
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• pp.133-138
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• 2003

The vascular relaxant and antihypertensive effects of newly developed salts of amlodipine-maleate and camsylate-were evaluated on isolated aorta from rats and in spontaneously hypertensive rats, and compared with those of amlodipine besylate, a standard drug. Amlodipine besylate concentration-dependently inhibited $Ca^{2＋}$-induced contraction in depolarised rat aorta($IC_{50}$/: 4.17 nM), with a very slow onset of action. Amlodipine maleate and amlodipine camsylate also showed vascular relaxant effect with a pattern and a potency similar to those of amlodipine besylate($IC_{50}$/: 3.62 and 3.28 nM, respectively). Amloclipine besylate produced a dose-dependent and long-lasting(>10∼24h) antihypertensive effect with a slow onset of action (ED$_{20}$: 2.31 mg/kg) in spontaneously hypertensive rats. Amlodipine maleate and amlodipine camsylate also exerted antihypertensive effects with a pattern and a potency similar to those of amlodipine besylate(ED$_{20}$: 2.09 and 2.21 mg/kg, respectively). These results suggest that amlodipine maleate and amlodipine camsylate are not statistically differ with amlodipine besylate in relaxant effect of $Ca^{2＋}$-induced contraction in depolarised rat aorta and in antihypertensive effect in spontaneously antihypertensive rats.

• Biomolecules & Therapeutics
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• v.17 no.3
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• pp.299-304
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• 2009

Rosiglitazone maleate (RGM) is widely used for improving insulin resistance. RGM is a moderate inhibitor of cytochrome P450 2C8 (CYP2C8) and is also mainly metabolized by CYP2C8. The aim of this study was to determine whether the effect of RGM on CYP2C8 is altered by co-treatment with other drugs, and whether amlodipine camsylate (AC) changes the pharmacokinetics (PK) of RGM. Of the 11 drugs that are likely to be co-administered with RGM in diabetic patients, seven drugs lowered the $IC_{50}$ value of RGM on CYP2C8 by more than 80%. In vitro CYP2C8 inhibitory assays of RGM in combination with drugs of interest showed that the $IC_{50}$ of RGM was decreased by 98.9% by AC. In a pharmacokinetic study, Sprague-Dawley (SD) rats were orally administered 1 mg/kg of RGM following by single or 10-consecutive daily administrations of 1.5 mg/kg/day of AC. No significant changes in the pharmacokinetic parameters of RGM were observed after a single administration of AC, but the AUC and $C_{max}$ values of RGM were significantly reduced by 36% and 31%, respectively, by multiple administrations of AC. In conclusion, RGM was found to be affected by AC by in vitro CYP2C8 inhibition testing, and multiple dosing of AC appreciably changed the pharmacokinetics of RGM. These findings suggest that a drug interaction exists between AC and RGM.

• Journal of Pharmaceutical Investigation
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• v.40 no.1
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• pp.15-21
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• 2010

Sibutramine is an orally administered centrally-acting antiobesity agent and inhibits both noradrenaline(norephinephirine) and serotonin(5-HT) reuptake. These effects are contributed by its active metabolites, M1 and M2. However, as the free base form of sibutramine is an oil form in room temperature, it had the problem of handling and stability. Thus, this drug should be used in the form of acid salt form in the pharmaceutical application. Unfortunately, anhydrous sibutramine hydrochloride is highly hygroscopic and unstable. In order to solve the hygroscopicity of the anhydrous salt form, another sibutramine acid salt form must be developed as a hydrate form. In this study. to overcome these problems, various of sibutramine acid salt forms were prepared with the pharmaceutically available salts such as maleate, esylate, mandelate, camsylate, besylate, salicylate, tartrate, isethionate and malate forms, and their physicochemical properties were investigated. Sibutramine malate was selected for excellent solubility and stability among the listed salt forms above. Its pharmacokinetic parameters were evaluated in rats comparing with sibutramine HCl, resulting in similar parameters. In vitro dissolution study of sibutramine malate-loaded capsule was performed comparison with commercial product ($Reductil^{(R)}$) in pH 1.2, pH 4.0, pH 6.8 and water medium. Our results indicated that there were no significant differences in their dissolution profiles were similar in all tested medium. Thus, sibutramine malate-loaded capsule should be a potential candiate due to its excellent solubility, good stability and biosimilar absorption.