LIPOSOMES WITH NIFEDIPINE AND NIFEDIPINE-CYCLODEXTRIN COMPLEX - CALORIMETRICAL AND PLASMA STABILITY COMPARISON

Inclusion complexes of nifedipine with 2-hydroxypropyl-beta-cyclodextr in (HP beta CD) were formed by the spray- and freeze-drying methods. N ifedipine or its inclusion complexes (Nifedipine-CD complex I and II) were incorporated into liposomes prepared by the ethanol injection met hod. The highest entrapment value (77.7% of the starting material) was achieved for liposomes with N-CD complex II. The interaction of nifed ipine with lipid bilayers was measured calorimetrically. DPPC liposome s mixed with nifedipine or N-CD complex II showed a slight shift of th e transition temperature of DPPC towards lower temperatures compared t o DPPC liposomes alone or mixed with HP beta CD. However, with nifedip ine, an additional transition peak was seen at lower temperatures in t he second and all subsequent scans which could not be detected for the N-CD complex. Plasma stability studies showed that liposomes containi ng N-CD complex II are more stable than liposomes containing nifedipin e. Encapsulation of drug-cyclodextrin complexes into liposomes can inc rease the entrapment of the lipophilic drug and reduce its release fro m the carrier.