Comparative bioavailability of two immediate release tablets of enalapril/hydrochlorothiazide in healthy volunteers

Pharmacokinetic-pharmacodynamic model of the antihypertensive interaction between telmisartan and hydrochlorothiazide in spontaneously hypertensive rats

OBJECTIVES

The goal of this study was to establish an integrated indirect response pharmacokinetic-pharmacodynamic model between telmisartan and hydrochlorothiazide to describe the antihypertensive interaction of these two drugs in spontaneously hypertensive rats.

METHODS

The blood pressure and plasma concentrations were measured by the tail-cuff test and high performance liquid chromatography-mass spectrometry, respectively, in spontaneously hypertensive rats. The current pharmacokinetic-pharmacodynamic model was based on the non-competitive pharmacodynamic interaction of two drugs acting on different physiological processes.

KEY FINDINGS

This model was able to acquire the temporal changes in drug concentration and blood pressure after administration of telmisartan or hydrochlorothiazide. The noncompetitive pharmacodynamic interaction assumed that the decreased blood pressure was attributed to the inhibitory function of telmisartan and stimulatory function of hydrochlorothiazide after administration of these two drugs. There was no significant pharmacokinetic change of telmisartan and hydrochlorothiazide in the different groups tested. The model predicted a synergistic pharmacodynamic interaction when telmisartan was administered in combination with hydrochlorothiazide, which was notably stronger than if the effects were additive.

CONCLUSION

The results showed that the presented pharmacokinetic-pharmacodynamic model was suitable for describing the antihypertensive interaction between telmisartan and hydrochlorothiazide.

An overview of chromatographic methods coupled with mass spectrometric detection for determination of angiotensin-converting enzyme inhibitors in biological material

Gas and liquid chromatography-mass spectrometry (GC-MS, LC-MS) methods for the determination of angiotensin-converting enzyme inhibitors (ACEIs) and their metabolites in biological material have been reviewed. Since 1980s those hyphenated techniques have been applied to quantitate ACE inhibitors and the dynamic increase in the number of relevant publications can be observed in recent years. Although most of the methods available in the literature were analyses of plasma or serum, assays of blood and urine were also included. Additionally, sample pretreatment methods, separation conditions and ionization modes were overviewed. Some information on chemical structures, cis-trans izomerization and stability of compounds in question was also included. Most of the reported methods were successfully applied to the pharmacokinetic studies in humans.

Evaluation of rapidly disintegrating tablets containing glycine and carboxymethylcellulose

A rapidly disintegration tablet in the oral cavity was prepared using a glycine as a disintegrant. Effect of disintegrant on the disintegration behavior of the tablet in the oral cavity was evaluated. Wetting time prepared from carboxymethylcellulose (NS-300) having the hardness of 4 kg was 3 s. Tablet containing NS-300 showed fastest disintegration compared to other formulations. These results suggested that NS-300 possessed excellent wetting nature and resulted in the rapid disintegration of tablet. Ethenzamide and ascorbic acid were added to the formulation, and their disintegration behavior were evaluated. Ethenzamide did not affect the disintegration property, however, ascorbic acid prolonged disintegration time. It was suggested that the tablet formulation containing NS-300 and glycine was highly applicable to water-insoluble drug, such as ethenzamide.