Liposomal Delivery of Ajmaline: Formulation Strategies, Pharmacological Rationale and Future Perspectives (Review Article)

Author(s): Shipra Varshney, Shabana Kausar Khan, Jagdish Chandra Nagar and Ahmed Jeelani*

Abstract: Ajmaline is a naturally occurring indole alkaloid isolated from Rauwolfia serpentina, and classified as a class IA antiarrhythmic agent. Today, ajmaline is especially important as a sodium-channel blocker that is used in the context of pharmacological provocation testing in order to ascertain the type-1 electrocardiographic pattern of the Brugada syndrome. Its pharmacological activity has been confirmed, but the traditional way of administering ajmaline carries with it the standard drawbacks of systemic drug delivery such as the requirement for a suitable concentration in the tissues to exert its intended effect and the risk of excessive exposure and undesirable pharmacological effects. Liposomes have been developed as a versatile drug delivery system, which can be loaded with both hydrophilic and lipophilic compounds, into the aqueous core and the lipid bilayer, respectively. They can be modified in their composition, particle size, surface charge and through their preparation to affect drug loading, stability, circulation and release. The pharmaceutical considerations related to the development of liposomal ajmaline are discussed here with special emphasis on the structure and classification of liposomes and their preparation techniques, mechanisms of drug loading, characterization of the liposomes, steric stabilization of the liposomes, mechanisms of drug release and potential targeting techniques. The liposomalization of ajmaline is discussed based on its physicochemical and pharmacological properties. Special emphasis is placed on the passive and active loading and the compromise of a long retention time with a proper drug release. Based on the literature available, it is suggested that liposomal delivery might also be used for the modification of the disposition and release characteristics of ajmaline; however, there is a lack of direct evidence of ajmaline loaded in liposomes. Thus, systematic formulation development, physicochemical characterization, pharmacokinetic study and pharmacodynamic assessment is necessary prior to clinical potential for liposomal ajmaline.

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