Enhanced Oral Absorption of All-trans Retinoic Acid upon Encapsulation in Solid Lipid Nanoparticles.

BACKGROUND: All-trans retinoic acid (ATRA) is widely employed in the treatment of various proliferative and inflammatory diseases. However, its therapeutic efficacy is imperiled due to its poor solubility and stability. Latter was surmounted by its incorporation into a solid matrix of lipidic nanoparticles (SLNs). METHODS: ATRA loaded SLNs (ATRA-SLNs) were prepared using a novel microemulsification technique (USPTO 9907758) and an optimal composition and were characterized in terms of morphology, differential scanning calorimetry (DSC), and powder X-ray diffraction studies (PXRD). In vitro release, oral plasma pharmacokinetics (in rats) and stability studies were also done. RESULTS: Rod-shaped ATRA-SLNs could successfully incorporate 3.7 mg/mL of ATRA, increasing its solubility (from 4.7 µg/mL) by 787 times, having an average particle size of 131.30 ± 5.0 nm and polydispersibility of 0.283. PXRD, DSC, and FTIR studies confirmed the formation of SLNs. Assay/total drug content and entrapment efficiency of ATRA-SLNs was 92.50 ± 2.10% and 84.60 ± 3.20% (n=6), respectively, which was maintained even on storage for one year under refrigerated conditions as an aqueous dispersion. In vitro release in 0.01 M phosphate buffer (pH 7.4) with 3% tween 80 was extended 12 times from 2h for free ATRA to 24 h for ATRA-SLNs depicting Korsmeyer Peppas release. Oral administration in rats showed 35.03 times enhanced bioavailability for ATRA-SLNs. CONCLUSION: Present work reports preparation and evaluation of bioenhanced ATRA-SLNs containing a high concentration of ATRA (>15 times than that reported by others). Latter is attributed to the novel preparation process and intelligent selection of components. Lay Summary: All-trans retinoic acid (ATRA) shows an array of pharmacological activities but its efficacy is limited due to poor solubility, stability and side effects. In present study its solubility and efficacy is improved by 787 and 35.5 times, respectively upon incorporation into solid lipid nanoparticles (ATRA-SLNs). Latter extended its release by 12 times and provided stability for at least a year under refrigeration. A controlled and sustained release will reduce dose related side effects. ATRA-SLNs reported presently can thus be used in treatment /prophylaxis of disorders like cancers, tuberculosis, age related macular degeneration and acne and as an immune-booster.

Effect of Acyclovir Solid Lipid Nanoparticles for the Treatment of Herpes Simplex Virus (HSV) Infection in an Animal Model of HSV-1 Infection.

BACKGROUND: Acyclovir use is limited by a high frequency of administration of five times a day and low bioavailability. This leads to poor patient compliance. OBJECTIVES: To overcome the problem of frequent dosing, we used nanotechnology platform to evaluate the proof of concept of substituting multiple daily doses of acyclovir with a single dose. METHODS: Acyclovir was formulated as solid lipid nanoparticles (SLN). The nanoparticles were characterized for particle size, surface charge and morphology and in vitro drug release. The pharmacokinetic and pharmacodynamic of SLN acyclovir were compared with conventional acyclovir in a mouse model. RESULTS: SLN showed drug loading of 90.22% with 67.44% encapsulation efficiency. Particle size was found to be of 131 ± 41.41 nm. In vitro drug release showed 100% release in SIF in 7 days. AUC0-∞ (119.43 ± 28.74 µg/ml h), AUMC0-∞ (14469 ± 4261.16 µg/ml h) and MRT (120.10 ± 9.21 h) were significantly higher for ACV SLN as compared to ACV AUC0-∞ (12.22 ± 2.47 µg/ml h), AUMC0-∞ (28.78 ± 30.16 µg/ml h) and MRT (2.07 ± 1.77 h), respectively (p<0.05). In mouse model, a single dose of ACV SLN was found to be equivalent to ACV administered as 400mg TID for 5 days in respect to lesion score and time of healing. CONCLUSION: The proof of concept of sustained-release acyclovir enabling administration as a single dose was thus demonstrated.

Solid lipid nanoparticles for ocular delivery of isoniazid: evaluation, proof of concept and in vivo safety & kinetics.

AIM: Evaluation of solid lipid nanoparticles (SLNs) for ocular delivery of isoniazid (INH). MATERIALS & METHODS: INH-SLNs were characterized for morphological, thermal, crystalline and nuclear magnetic resonance properties. In vitro release and ex vivo corneal permeability of INH-SLNs was also evaluated. Proof-of-concept uptake studies were performed in corneal and conjunctival cell lines and in vivo in rat eye using fluorescein-labeled SLNs. Antimycobacterial activity of INH-SLNs was confirmed. In vivo aqueous humor pharmacokinetics, toxicity and tolerance was performed in rabbit/rat eye. RESULTS: INH-SLNs showed extended release (48 h), enhanced corneal permeability (1.6-times), five-times lower MIC, significant in vitro and in vivo uptake of fluorescein-labeled SLNs, 4.2-times ocular bioavailability (area under the curve) and in vivo acute and repeat dose safety. CONCLUSION: INH-SLNs are an effective ocular delivery system.

Topical delivery of TRPsiRNA-loaded solid lipid nanoparticles confer reduced pain sensation via TRPV1 silencing, in rats.

Present work describes a novel composition for encapsulating TRPsiRNA (TRPV1-targeting siRNA) within lipid-matrix (4:1::glyceryl behnate:stearic acid) of SLNs, using suitably modified cold high-pressure homogenisation technique. Optimisation of the method and composition conducted using calf-thymus DNA (ctDNA), to avoid cost of TRPsiRNA molecules, resulted in small size (d50 = 50-100 nm) and high entrapment (77.22-98.5%). Complete masking of extreme negative charge of both ctDNA (-34.50 mV) and TRPsiRNA (-23.98 mV) upon encapsulation in SLNs without employing cationic components is reported herein for the first time. Diffusion-controlled release (90.17% at 72 h) from a rigid matrix shifted to porous matrix (at 24 h) due to solubilisation of stearic acid at 37 °C. Efficient in vitro (HEK293 T cells) and in vivo transfection and expression established the proof-of-concept. PEG600 as supporting-surfactant and vitrifying agent promoted small size, effective transfection and rupture of endosomal membrane to affect endosomal escape. Physiological efficacy in terms of significant increase (p < .0001) in paw-withdrawal-latency, following topical and intradermal application of TRPsiRNA-loaded SLNs, in rats, exposed to thermal hyperalgesia (145 and 182%, respectively) and capsaicin-induced pain (155 and 182%, respectively) indicate effective silencing of skin TRPV1. Significant decrease in intensity and duration (one-fifth) of capsaicin-induced nocifensive behaviour was also observed. Naked TRPsiRNA, however, did not show any effect.

Role of novel delivery systems in developing topical antioxidants as therapeutics to combat photoageing.

Ageing proceeds by highly complicated biochemical processes, in which the involvement of the reactive oxygen species (ROS) and free radicals has been implicated. Reactive oxygen species are dramatically enhanced by exposure to the ultraviolet radiation. Free radical scavengers and antioxidants can thus provide a long-term protection against these changes. Currently, dermaceutical and cosmetic industry is growing immensely with its main focus on packaging the active into a suitable/novel delivery system. This not only enhances the customer acceptance but offers better targeting to the upper skin layer, with faster onset, at a lower concentration of the active. Later also counter toxic or adverse effects observed with large doses especially when administered orally. Several of the antioxidant molecules are labile to degradation in the presence of oxygen, water and light, hence it becomes all the more appropriate to use a delivery system which will augment their stability and hence enhance the performance. In the present review, we focus on the pioneering research on novel delivery systems which can promote the therapeutic value of antioxidants for combating UV-induced photoageing.

Study of the extent of ocular absorption of acetazolamide from a developed niosomal formulation, by microdialysis sampling of aqueous humor.

Acetazolamide, a carbonic anhydrase inhibitor is used orally (no topical formulation being available in the market) for the reduction of intraocular pressure (IOP) in patients suffering from glaucoma. Two major reasons responsible for the failure to develop a topically effective formulation of acetazolamide are its low solubility (0.7mg/ml) and its low permeability coefficient. It is generally recognized that topical acetazolamide formulation possessing efficacy similar to that achieved upon oral administration would be a significant advancement in the treatment of glaucoma. In order to enhance the bioavailability of acetazolamide by topical route and to improve the corneal permeability of the drug, the niosomes of acetazolamide were prepared (by reverse phase evaporation method) and coated with Carbopol for the latter's bioadhesive effect. The pharmacodynamic studies showed 33% fall in IOP with the developed formulation, and the effect was sustained for 6h after instillation. The effect compared well with a four times higher concentration of dorzolamide (Dorzox, a topical CAI available in the market. In the present study, the aqueous humor disposition of the drug from the developed bioadhesive coated niosomal formulation (ACZREVbio) is compared with the aqueous suspension of the drug (containing 1% (w/v) Tween 80 as a dispersing agent) at similar concentrations. The concentration of acetazolamide absorbed in the aqueous humor at various times from the control suspension and from ACZREVbio was determined by microdialysis in male albino rabbits. Microdialysis provides a complete concentration versus time profile and hence is an important advance to the regional sampling of tissues. The peak concentration of drug absorbed in the aqueous humor from the ACZREVbio formulation (14.94microg/ml) was almost two times of that obtained with the equivalent amount of acetazolamide control suspension (6.93microg). The results show a significant broadening of peak from 80 to 120min with the concentration of more than 13microg being maintained at these times, for the bioadhesive coated niosomal formulation (ACZREVbio). An important observation was the fact that a high drug concentration of 12.02microg reached immediately, i.e., 20min after instillation of ACZREVbio indicating a high penetration being achieved, while a meagre concentration of only 3.53microg is obtained at 60min after instillation of the control suspension. The aqueous humor disposition indicates peaks and troughs in drug concentration which may be related to the decrease in aqueous humor formation, such that the drug concentration/volume increased at these points.

Nanotechnology: a new paradigm in cosmeceuticals.

Nanotechnology is the creation of functional materials, devices and systems through control of matter on the nanometer length scale, and exploitation of novel phenomena and properties (physical, chemical, biological, mechanical, electrical...) at that length scale. In the area of cosmetics and anti-aging, in particular, as well as in the pharmaceutical arena, nanotechnology has played an important role in delivering active ingredients to the skin, in both patch delivery and timed release application. Nanoparticles/nanospheres, nanospheres sounds like futuristic technology. The revolution they triggered is apparent from the fact that cosmetics are no longer visualized as products that cover up or camouflage imperfections in personal appearance. The latest trend in these products is to combine clinically proven ingredients with patented delivery systems and the aesthetics of fine cosmetics. Cosmeceutical products are those poised on the gap between cosmetic products that simply cleanse and beautify and pharmaceuticals that cure and heal. According to The Freedonia Group Inc. Cleveland Ohio, the demand for formulated appearance-enhancing products is projected to increase by more than 12% per year up to 2007 to reach $2.5bn, making cosmeceuticals one of the most dynamic sectors within the cosmetics and personal care markets. Cosmetic industries rank high among the nanotechnology patent holders in U.S.; L'Oreal which devotes about $600 million of its annual $17 billion revenues to research is the industry leader on nanopatents. This report directly addresses the science behind the use of nanotechnology for the development of cosmetics. Further, the products launched by various cosmetic giants will be discussed at length.

Improved pharmacodynamics of timolol maleate from a mucoadhesive niosomal ophthalmic drug delivery system.

In the present study chitosan (REVTMbio1) or Carbopol (REVTMbio2 and 3) coated niosomal timolol maleate (0.25%) formulations were prepared by reverse phase evaporation (REV) and compared to timolol solution (TMS; 0.25%) in terms of in vitro release and IOP lowering pharmacodynamic effect. The in vitro release phase of timolol (91% release in 2 h) was extended significantly by its incorporation into niosomes and further by the polymer coating (40-43% release upto 10 h). The developed formulations were evaluated for their pharmacodynamics in albino rabbits, by measuring intraocular pressure (IOP) using a non-contact pneumatonometer, and were compared to a marketed in situ gel forming solution of timolol (Timolet GFS, 0.5%; Sun Pharma). REVTMbio1 formulation showed a more sustained effect of upto 8h (vis a vis 6 h for carbopol-coated niosomes). TMS in comparison showed effect for only 2 h though the peak effect was slightly more (14%). Lowering of IOP in the contralateral eye (20-40% as compared to 100% in case of TMS), considerably reduces with REV and REVbio formulations indicating lesser systemic side effects. Moreover, the results of REVTMbio1formulation containing 0.25% of timolol maleate compared well with the 0.5% marketed gel formulation, indicating our formulation to be significantly better considering that similar effect is obtained at half the concentration. The later becomes especially important in context to the cardiovascular side effects associated with ocular timolol maleate therapy.

Development of a topical niosomal preparation of acetazolamide: preparation and evaluation.

Orally administered acetazolamide has a limited use in glaucoma due to the systemic side effects associated with its use. No topical formulation of acetazolamide is available, mainly because of it having a limited aqueous solubility and poor corneal permeation. To enhance the bioavailability of acetazolamide by the topical route and to improve the corneal permeability of the drug, niosomes of acetazolamide were prepared (employing span 60 and cholesterol) by different methods. Transmission electron microscopy (TEM) of the selected formulation was carried out to study the morphology. Niosomes were also prepared in the presence of dicetyl phosphate and stearylamine to obtain negatively and positively charged vesicles, respectively. It was found that the reverse-phase evaporation method (REV) gave the maximum drug entrapment efficiency (43.75%) as compared with ether injection (39.62%) and film hydration (31.43%) techniques. Drug entrapment efficiency varied with the charge and the percent entrapment efficiency for the REV method was 43.75, 51.23 and 36.26% for neutral, positively charged and negatively charged niosomes, respectively. Corneal permeability studies, however, showed that the percent permeation and the apparent permeability coefficient for the charged niosomes were less than for the neutral ones. A bioadhesive niosomal formulation of acetazolamide was also prepared and compared with the positively charged formulation, considering that both of them would have a prolonged stay in the cul-de-sac because of their expected interactions with mucin. The formulations were also compared based on their intraocular pressure (IOP)-lowering capacity. The positively charged niosomes (REV2), although showing good corneal permeability and pharmacodynamics, were however found to be inappropriate in terms of the corneal cell toxicity. The bioadhesive coated formulation (REV1bio) compared well with REV2 and also showed a much lesser toxicity. Further, the IOP-lowering effect of the developed formulations was compared with that of a marketed formulation of dorzolamide 2%, a topical carbonic anhydrase inhibitor. The developed niosomal formulations of acetazolamide showed a comparable physiological effect (33% reduction of IOP in REV1bio and 37% reduction in dorzolamide) with a duration of up to 6 h (the duration being 3 h for dorzolamide). Results of the study indicate that it is possible to develop a safe (as indicated by corneal toxicity studies) and physiologically active topical niosomal formulation of acetazolamide relative in efficiency to the newer local carbonic anhydrase inhibitor, dorzolamide. The developed formulations can form a cost effective treatment plan, which is especially important in the treatment of glaucoma, a chronic ailment affecting middle-aged to old patients.

Vesicular systems in ocular drug delivery: an overview.

The main aim of pharmacotherapeutics is the attainment of effective drug concentration at the intended site of action for a sufficient period of time to elicit a response. Poor bioavailability of drugs from ocular dosage form is mainly due to the tear production, non-productive absorption, transient residence time, and impermeability of corneal epithelium. Though the topical and localized application are still an acceptable and preferred way to achieve therapeutic level of drugs used to treat ocular disorders but the primitive ophthalmic solution, suspension, and ointment dosage form are no longer sufficient to combat various ocular diseases. This article reviews the constraints with conventional ocular therapy and explores various novel approaches, in general, to improve ocular bioavailability of the drugs, advantages of vesicular approach over these and the future challenges to render the vesicular system more effective.