Category: Formulation and Quality
Purpose: Acquired immunodeficiency syndrome (AIDS) continues to be a serious health issue worldwide, with 1.8 million new cases of HIV, 36.9 million people living with human immunodeficiency virus (HIV) in 2017 and an estimate of 940,000 people have died from AIDS-related illnesses in 2017. Oral administration of drugs is the preferred option in patients affected by chronic diseases including HIV. Most of the marketed antiretrovirals’ (ARVs) are administered orally, however various conventional (marketed) and innovative (under investigation) oral delivery systems must overcome numerous challenges, including the acidic gastric environment, poor aqueous solubility and physicochemical instability of many of the approved ARVs. Lipid based drug delivery system is one of the innovative research strategies which could overcome the limitations of the present treatment regimens and also enhance the efficacy of the oral ARV therapy in HIV. In our study, we aimed to design proliposomes as a carrier for the delivery of efavirenz (EFA), a first line ARV drug in the high activity antiretroviral therapy, to improve the solubility and bioavailability following oral administration.
Methods: Preparation of Proliposomes: Proliposomal powder formulations loaded with efavirenz (drug: lipid: cholesterol was 1:1:0.1 w/w/w) were prepared using various lipids such as hydrogenated soy phosphatidylcholine (SPC) (F1), dimyristoyl phosphatidylcholine (DMPC) (F2) and microcrystalline cellulose as adsorbent. Solvent was evaporated under reduced pressure using a rotary vacuum evaporator; passed through the sieve (250µm; 60 mesh) to obtain free flowing proliposomal powder which was further used for evaluation. The selected proliposomal powder was dispersed, hydrated (20 min) in nanopure water, centrifuged (5000 rpm) for 5 min to separate the liposomes (supernatant) from the excipients. Resultant dispersion was used to determine the particle size (Z-average mean size and polydispersity index) and z - potential using a Nanosizer. Apparent bulk and tapped bulk properties were measured to evaluate the flow properties of the prepared powder using cylinder method. Selected proliposomal powder formulation was compressed into tablets using magnesium stearate and talc (2%) each using Mini rotary tablet press. Tablets were tested for quality control tests such as weight variation, thickness diameter, hardness, friability and disintegration time.
In vitro dissolution testing
EFA proliposomal Powder –Type IV apparatus CE7-smart (SOTAX®): EFA release was examined using 1% SLS as dissolution medium at 370C for 24 hours. Briefly, proliposomal powder containing EFA was placed on the top of the layer of beads in the dissolution flow through cells with a diameter of 22.6 mm. Samples were collected at different time intervals into the fraction collector and analyzed using HPLC.
EFA proliposomal tablets – Type II Vankel Dissolution apparatus VK7000: EFA release was examined using 1% SLS as dissolution medium at 370C for 24 hours at 50 RPM.
Quantification of EFA using HPLC: Using Agilent 1260 Infinity attached to autosampler and PDI detector, samples were analyzed using acetonitrile: water as mobile phase (pH adjusted to 3.2 with formic acid) at a flowrate of 1 ml/min at 250C at 247 nm; injection volume was 10 µL.
Results: Based on the powder flow properties, proliposomal formulation (F2) using DMPC, cholesterol, EFA was further used for evaluation. Evaluation of powder flow properties of F2 indicated that the hausner ratio was 1.167, compressability index was 13.51 and assay was 102.75 ±1.26. Characterization of hydrated proliposomal formulations revealed that the Z-average size was 470.77 ±7.617 nm; PDI of 0.41 ± 0.06 and zeta potential was 26.23 ± 3.45 mV. Results of proliposomal powder compressed into tablets indicated that the weight variation (%) was 0.0710 ±0.068; hardness (kg/cm2) was between 5 - 6; friability (%) was 0.04 and thickness (mm) was 6.24± 0.04 with disintegration time of 15 min. In vitro dissolution studies conducted using USP type IV apparatus (using 1% SLS), in a continuous flow through cell showed that the extent of EFA released from proliposomal powder was 81.26 % and with the pure drug was 55.59 % at the end of 6 hours. To compare with USP Type II, dissolution of EFA proliposomal tablet was performed, which showed a release of 53.4 % with proliposomal tablet and 40.3 % with the pure drug (no lipids) at end of 4 hours. Although the dissolution was carried out in a discriminatory media (1% SLS) from the OGD media (2% SLS), we observed 1.46 % fold increase from proliposomal powder and 1.32 % increase from proliposomal tablet in comparison with pure drug indicating an improvement in the release profile of EFA.
Conclusion: EFA proliposomal powder was successfully formulated with good flow properties, which could be incorporated into solid dosage forms. An increase of 1.46 fold in the in vitro dissolution profile of EFA necessitates further confirmation using artificial in vitro permeation assay and in vivo evaluation.
Betageri GV. (2005). Proliposomal drug delivery system. US Patent 6,849,269.
Brocks DR, Betageri GV. (2002). Enhanced oral absorption of halofantrine enantiomers after liposomal encapsulation. J Pharm Pharmacol 54:1049–53.
Surya Kovvasu– Post Doctoral Fellow, Western Univeristy of Health Sciences, Pomona, California
Rohit Joshi– Western University of Health Sciences, Pomona, California
Guru Betageri– Western University of Health Sciences, Pomona, California