Three Generations of Cyclosporine A Formulations: An In Vitro Comparison

Abstract

When the microemulsion formulation of the critical dose drug cyclosporine A (CsA) (Sandimmun Optoral) was introduced in the mid-1990s, it became clear that this new formulation improves the oral bioavailability of CsA and has a positive influence on its pharmacokinetic variability. Previous studies with the original CsA formulation (Sandimmun) showed that the size of the emulsion droplets and concomitant food intake has an effect on the absorption of CsA from the small intestine when orally administered. It was suggested that these effects might have an influence on the drugs' pharmacokinetic parameters. In this study, we focused on the two above-mentioned aspects and compared the first and second generations of CsA products (Sandimmun, Sandimmun Optoral) to generic CsA formulations by analyzing the contents of cyclosporine A gel capsules with respect to their emulsion droplet and micelle sizes using photon correlation spectroscopy (PCS). We tried to discern any differences in droplet size between different generations of CsA formulations, primarily the second and third generation, through simple physical tests. Because a high fat content food may influence the absorption of CsA, we also determined the distribution of CsA between hydrophilic and lipophilic phases using high-performance liquid chromatography analysis. It became clear that when compared under simple physical conditions, established cyclosporine formulations and new generic products show significant differences in droplet size and distribution between an aqueous phase and a high fat content food. Whether these differences are of clinical relevance remains to be investigated.

Generic and therapeutic substitution: a viewpoint on achieving best practice in Europe

“…The premise on which generic substitution rests is that the substituted drug is equivalent to the original drug. However, there are documented examples where pharmacological variations exist, even between originator and generic formulations and between different generic formulations of the 'same' drug [1,2]. Although two formulations may be considered bioequivalent at a population level, individuals may fall outside of this range with some receiving higher or lower doses than expected [3,4], irrespective of the manufacturer -branded or generic.…”

Nanomedicines in renal transplant rejection ? focus on sirolimus

“…In addition, other particular drug carriers, such as emulsion, liposome, and polymeric micelle, are considered as alternative methods to deliver water insoluble drugs (Yokoyama 2005). For example, cyclosporine has been emulsified by bile salts to form micelles and further modified into microemulsion from the olive oil-based solution to enhance bioavailability (Thomas et al 2005). The liposomal formulation of tacrolimus also has been demonstrated as an effective strategy to increase efficacy and decrease toxicity (McAlister et al 1999; Alemdar et al 2004).…”