In vitro interaction of Amoxicillin with Calcium Chloride (Fused) at pH 2.4 and pH 7.4.

This study was aimed to evaluate the in vitro complexation nature and strength of complex which may be formed due to interaction between Amoxicillin and Calcium chloride (CaCl2). The interaction of Amoxicillin and Calcium chloride (fused) has been studied in aqueous systems at a fixed temperature (37 ± 0.5) °C and under different pH (pH 2.4 and pH 7.4) by using some physical methods as spectral observation, Job’s method of continuous variation, Ardon’s method. From spectrophotometric study, Amoxicillin gives a sharp peak at 272 nm when Calcium chloride mixed with Amoxicillin in 1:1 ratio the intensity of the peak of Amoxicillin change remarkably due to interaction. The jobs plot was obtained by plotting absorbance difference against the mole fraction of the each drug at pH 2.4 and pH 7.4. Amoxicillin forms strong 1:1 complex with Calcium chloride and reverse V Shaped curves indicate the formation of 1:1 complexes of Amoxicillin with Calcium chloride. These may indicate strong kinetics of complexation between Amoxicillin with Calcium chloride. The value of stability constant for the complexation of Amoxicillin with calcium chloride at pH 2.4 and pH 7.4 were obtained from the spectral data using Ardon’s plot. The value of stability constant for the drug-metal system at pH 2.4 and pH 7.4 are 5.54 and 6.67 respectively. At pH 2.4 it is found that Amoxicillin form relatively stable complex with Calcium chloride (stability constant 6.67) is high in comparison to pH 7.4. It can therefore be concluded that a careful consideration is needed during concurrent administration of Amoxicillin with Calcium chloride.

In vitro study on the interaction of ketotifen fumarate with anhydrous theophylline

The purpose of the present study was to investigate the interaction between ketotifen fumarate and anhydrous theophylline in aqueous media of various pH (1.2 and 6.8). Using Job's continuous-variation analysis and Ardon's spectrophotomeric measurement methods, the values of the stability constants of theophylline with ketotifen were determined at a fixed temperature (37 ºC) at various pH. The stability constants, ranging between 5.66 and 9.92, were derived from Ardon's plot, indicating that comparatively stable complexes had formed as a result of an interaction between the drugs. However, following the interaction of theophylline with ketotifen, stability constants were <1 at gastric pH (1.2) and intestinal pH (6.8). Concurrent administration of ketotifen and theophylline could result in the formation of a stable complex and this is likely to reduce the therapeutic activities of both drugs.

O objetivo do presente estudo foi investigar a interação entre o fumarato de cetotifeno e a teofilina anidra em meios aquosos com vários pH (1,2 e 6,8). Utilizando a análise da variação contínua de Job e os métodos de medida espectrofotométrica de Ardon, os valores das constantes de estabilidade da teofilina com o cetotifeno foram determinados em temperatura fixa (37 oC) em vários pH. As constantes de estabilidade, variando entre 5,66 e 9,92 derivaram-se a partir do delineamento de Ardon, indicando, comparativamente, que complexos estáveis se formaram como resultado da interação entre os fármacos. Entretanto, seguindo a interação da teofilina com o cetotifeno, as constantes de estabilidade foram <1, em pH gástrico (1,2) e intestinal (8,8). A administração concomitante de cetotifeno e teofilina poderia resultar na formação de complexo estável, o que reduz a atividade terapêutica de ambos os fármacos.

In-vitro interaction of verapamil hydrochloride with magnesium sulphate (anhydrous) and its influence on protein binding of verapamil hydrochloride.

The interaction between Verapamil Hydrochloride and Magnesium Sulphate (anhydrous) has been studied in an aqueous system at pH 7.4 and 2.4. From spectrophotometric study, it has been found that Verapamil Hydrochloride form 1:1 complex with Magnesium Sulphate (anhydrous). Spectral studies helps to detect the initial complexation between drug and metal. Job’s plot at 7.4 and 2.4 provides same type of information. The Ardon’s spectrophotometric method confirmed the 1:1 complexation and the value of stability constants was calculated using Ardon’s plot. An in vitro study of protein binding of Verapamil Hydrochloride and their 1:1 mixture with Magnesium Sulphate (anhydrous) has been conducted by equilibrium dialysis method at (37 ± 0.5)0C and at pH 7.4. The Scatchard plots were prepared to reveal the number of binding sites and the affinity for protein binding. It has been found that interaction of the drug with Magnesium Sulphate (anhydrous) results into increasing the affinity and increasing the protein binding of Verapamil Hydrochloride.