Purpose: Nicardipine hydrochloride has been used widely for the treatment of angina pectoris and hypertension. Because of its extensive first pass metabolism after oral administration, the transdermal administration of nicardipine microemulsions was developed in this study.
Methods: Microemulsions consisted of isopropyl myristate (IPM), surfactant mixture of Tween 80/Span 80 and/or Tween 80/Span 20, co-surfactant (ethanol) and aqueous phase. Pseudo-ternary phase diagrams were constructed using water titration method. The effect of component of microemulsion on the percutaneous absorption of drug was evaluated by in vitro permeation study.
Results: The area of microemulsion isotropic region in the presence of ethanol was comparably larger in the absence of ethanol. The mean droplet size of nicardipine microemulsions ranged from 70 to 123 nm. With addition of ethanol, the droplet size became smaller. The permeation rate and extent of nicardipine microemulsion transport across rat skin was affected by the components of microemulsion. Nicardipine microemulsion had higher flux at surfactant mixture with lower hyrophile-lipophile balance (HLB) value and Tween content.
Conclusions: The microemulsion consisted of 52% IPM, 35% surfactant mixture and 13% water had higher permeation rate through rat skin above 122.53 ± 1.87 μg/cm2/h and was expected to develop a transdermal delivery system.