Infrared Spectroscopy Case Study

.2. Preformulation of GRMDDS of BCLF and DLTH
Numerous characterizations can be employed during the preformulation stage of drug development, and each has its associated utility and function for the physical characterization of a drug substance. However, when a large amount of information is to be extracted from a small amount of sample, spectroscopic methods of analysis can be of utmost value.148 Preformulation studies are carried out in the initial stages of dosage form development. Its basic rationale is to understand the fundamental physical and chemical properties of the drug molecule alone and other excipients used in the development of dosage forms. From these studies one can get the information and decide on the approaches in the formulation

Infrared spectroscopy (IR) is a well-known method of drug analysis and has an exclusively great significance in investigations of interactions between drugs and excipients in pharmaceutical formulations. Infrared spectroscopy (IR) is a well-known method of drug analysis and has an exclusively great significance in investigations of interactions between drugs and excipients in pharmaceutical formulations.149. Excipients are believed to be as inert substance but they can have considerable impact on ultimate pharmacological availability of drug substances when added to a formulation. The magnitude of this effect depends on the physiochemical characteristics of the drug and quantity and properties of the excipients.150 Studies of drug-excipient compatibility represent an important phase in the preformulation stage of the development of solid dosage forms. The potential physical and chemical interactions between drugs and excipients can affect the chemical nature, the stability and bioavailability of drugs and consequently, their therapeutic efficacy and safety.151 The occurring interactions between drug(s) and excipients are discovered and proved by IR spectroscopy with the following important characteristics: appearance of new IR absorption band(s), broadening of band(s), and alteration in

The DSC analysis of the drug alone elicited an endothermic peak very close to the reported value of baclofen’s melting point.153 This confirmed that the presence of other excipients did not affect the drug stability. Differential scanning calorimeter results revealed that the physical mixture of diltiazem with polymers showed superimposition of the thermograms. The DSC thermograms are shown in figure 6.2.10. A sharp endotherm was observed for diltiazem hydrochloride at 217.49o. This melting endotherm was also observed at 211o, indicating absence of drug to polymer interactions. Fig.6.2.11 shows the DSC thermograms of DLT, physical mixture and formulation. The thermogram of hibiscus esculentus showed an endothermic peak at 80.39°C. The DSC thermogram of xanthan gum showed two endothermic peaks at 71.78 & 241°C and an exothermic one at 300°C at which the decomposition of xanthan gum occurred. The thermogram of DTZ HCl showed a single sharp endothermic peak at 215°C. The physical mixtures showed the characteristic endothermal peaks of the drug, while, the thermogram of DTZ HCl physical mixture showed broad endothermic peaks only, with complete disappearance of the drug melting peak as a result of drug. These results agree with that of Sultana et al., 2009, who found that, the endothermic peak of DTZ HCl in alginate microspheres was not distinctive indicating