Effect of small levels of impurities on the water vapor sorption behavior of ranitidine HCl.

Purpose: Deliquescence is the process by which a solid undergoes dissolution by sorbing moisture from its surroundings when a characteristic relative humidity, RH0, is reached. For mixtures of two or more deliquescent solids, RH0 will generally be lowered. The goal of this research was to investigate the effect of small amounts of impurities or degradants on RH0 for a model deliquescent pharmaceutical salt.

Deliquescence-induced caking in binary powder blends.

In this study, moisture-induced caking of deliquescent crystalline powder blends was investigated. Physical mixtures of sugars and citric acid anhydrous showed significant cake formation when cycled above and below the mixture critical relative humidity. It was found that combinations of glucose and citric acid underwent efflorescence to form crystalline solid bridges while fructose and citric acid cakes contained amorphous material.

Role of deliquescence lowering in enhancing chemical reactivity in physical mixtures.

Mixtures of deliquescent solids are susceptible to deliquescence lowering, where water vapor condensation occurs in mixtures at a lower critical relative humidity (RH(0mix)) than individual component critical relative humidities (RH(0)s). The purpose of this study was to evaluate the effect of deliquescence lowering on chemical reactivity. Sucrose, citric acid and their physical mixtures were characterized using vapor sorption analysis to determine RH(0) and RH(0mix).

Physical stability of crystal hydrates and their anhydrates in the presence of excipients.

There are few studies in the literature that deal with the effect of excipients on the kinetics of vapor phase induced hydrate-anhydrate phase transformations. The main purpose of this study was to probe the phase stability of hydrate-anhydrate systems in the presence of hygroscopic and nonhygroscopic excipients following exposure to either dehydrating or hydrating conditions. Physical mixtures and compacts of model hydrate formers (theophylline and carbamazepine) and excipients (mannitol, microcrystalline cellulose (MCC), polyvinylpyrrolidone (PVP) K12 and K90) were stored at 22 degrees C and varying relative humidities.

Deliquescence in binary mixtures.

Purpose: Deliquescence is a first-order phase transformation from solid to solution and occurs at a specific relative humidity (RH) that is characteristic to the solid. The goal of this research was to investigate the reduction in critical relative humidity (RH0) in binary solid mixtures of deliquescent active pharmaceutical ingredients (APIs) and deliquescent excipients.

Methods: The RH where deliquescence is induced, RH0, was measured using a gravimetric water vapor sorption balance.