Enhancement of In Vitro Skin Transport and In Vivo Hypoglycemic Efficacy of Glimepiride Transdermal Patches

Purpose: To utilize hydroxybutyl-β-cyclodextrin (HB-β-CD) and polyvinyl pyrrolidone (PVP) for the enhancement of the transdermal delivery of glimepiride (GMD).Methods: Matrix-type transdermal patches containing GMD, drug  coprecipitate or its inclusion complex were prepared using different gelling agents, viz, hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), carbopol and chitosan. In vitro skin permeation evaluation of the formulations was conducted using automated diffusion system. Selected patch formulations were assessed for hypoglycemic activity as well as for GMD plasma concentration in rats.Results: GMD- hydroxybutyl-β-cyclodextrin (HB-β-CD) binary systems (1:2 molar ratio) enhanced GMD aqueous solubility by > 10-fold. Diffusion test showed improved release of GMD-HB-β-CD inclusion complex compared with GMD alone. Maximum cumulative amounts of GMD- HB-β-CD that permeated through rat skin was 26.97 and 14.28 µg/cm2 for patches prepared with fchitosan and HPMC, respectively. Thus, GMD-chitosan  patches showed significantly higher (p < 0.05) drug permeation than GMD-HPMC after 6 h. Both chitosan and HPMC patches of GMD-HB-β-CD demonstrated substantial reduction (p < 0.05) in blood glucose level (192.67 ± 21.18 and 201 ± 15.11 mg/ dl, respectively), compared with the baseline value of 240 mg/ dl.Conclusion: Application of chitosan and HPMC transdermal patches of GMD-HB-β-CD can serve as a potential alternative to peroral GMD with improved bioavailability and patient compliance.Keywords: Glimepiride, Transdermal patch, Coprecipitate, Inclusion complex, Hydroxypropyl methylcellulose, Polyvinyl pyrrolidone, Chitosan, Skin permeatio

Dimethyl sulfoxide blocks herpes simplex virus-1 productive infection in vitro acting at different stages with positive cooperativity. Application of micro-array analysis

BACKGROUND: Dimethyl sulfoxide (DMSO) is frequently used at a concentration of up to 95% in the formulation of antiherpetic agents because of its properties as a skin penetration enhancer. Here, we have analyzed the effect of DMSO on several parameters of Herpes Simplex Virus replication. METHODS: Productive infection levels of HSV-1 were determined by plaque assay or by reporter gene activity, and its DNA replication was estimated by PCR. Transcript levels were evaluated with HSV-specific DNA micro-arrays. RESULTS: DMSO blocks productive infection in vitro in different cell types with a 50% inhibitory concentration (IC(50)) from 0.7 to 2% depending upon the multiplicity of infection. The concentration dependence exhibits a Hill coefficient greater than 1, indicating that DMSO blocks productive infection by acting at multiple different points (mechanisms of action) with positive cooperativity. Consistently, we identified at least three distinct temporal target mechanisms for inhibition of virus growth by DMSO. At late stages of infection, DMSO reduces virion infectivity, and markedly inhibits viral DNA replication. A third mode of action was revealed using an oligonucleotide-based DNA microarray system for HSV. These experiments showed that DMSO reduced the transcript levels of many HSV-1 genes; including several genes coding for proteins involved in forming and assembling the virion. Also, DMSO markedly inhibited some but not all early transcripts indicating a previously unknown mode for inhibiting the early phase of HSV transcription-replication cycle. CONCLUSION: These observations suggest that DMSO itself may have a role in the anti-herpetic activity of formulations utilizing it as a dispersant

Enhanced transdermal peptide delivery and stability by lipid conjugation: Epidermal permeation, stereoselectivity and mechanistic insights

Purpose: Efficient delivery of therapeutic peptides to the skin will facilitate better outcomes in dermatology. The tetrapeptide AAPV, an elastase inhibitor with potential utility in the management of psoriasis was coupled to short chain lipoamino acids (Laa: C6-C10) to enhance the peptide permeation into and through human epidermis.Methods: AAPV was conjugated to Laas by solid phase synthesis. Peptide stability, skin distribution and permeation, elastase activity and surface activity were determined.Results: Laas increased peptide permeation into the skin. The permeation lag time and amount of peptide remaining in the skin increased with the carbon chain length of the Laa conjugate. We also demonstrated stereoselective permeation enhancement in favour of the D-diastereomer. Importantly, the elastase inhibition activity of the peptide was largely retained after coupling to the Laa conjugates, showing potential therapeutic utility. The Laa-peptide structures were shown to be surface active, suggesting that this surfactant-like activity coupled with enhanced lipophilicity may contribute to their interaction with and permeation through the lipid domains of the stratum corneum.Conclusions: This study suggests that the Laa conjugation approach may be useful for enhancing the permeation of moderately sized peptide drugs with potential application in the treatment of skin disorders

Therapeutic Paint of Cidofovir/Sucralfate Gel Combination Topically Administered by Spraying for Treatment of orf virus Infections

The aim of the research was to study a new cidofovir/sucralfate drug product to be used as a spray for treating the mucosal and/or skin lesions. The product, i.e., a water suspension of sucralfate (15% w/w) and cidofovir (1% w/w), combines the potent antiviral activity of the acyclic nucleoside phosphonate cidofovir ((S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine) and the wound healing properties of sucralfate gel (sucrose octasulphate basic aluminum salt). The product was characterized in vitro with respect to compatibility between drug and carrier, spray particle size, spray deposition, drying kinetics, and drug content and release. An interaction between the two active substances was found. The interaction between sucralfate and cidofovir was counteracted by introducing sodium dihydrogen phosphate (16% w/w) in the preparation. The spray formulation containing cidofovir/sucralfate gel painted the skin and dried quickly to a scab, remaining firmly adhered to the lesions. The therapeutic paint was tested in vivo on lambs infected with orf virus by treating the animals with different cidofovir/sucralfate formulations (0.5% or 1% cidofovir + sucralfate 15% + NaH2PO4 16% w/w) and with sucralfate gel suspension alone as control. The treatment with formulations containing cidofovir and phosphate salt for four consecutive days resulted in a rapid resolution of the lesions, with scabs containing significantly lower amounts of viable virus when compared with untreated lesions and lesions treated with sucralfate suspension alone

Ocular Drug Delivery

Ocular drug delivery has been a major challenge to pharmacologists and drug delivery scientists due to its unique anatomy and physiology. Static barriers (different layers of cornea, sclera, and retina including blood aqueous and blood–retinal barriers), dynamic barriers (choroidal and conjunctival blood flow, lymphatic clearance, and tear dilution), and efflux pumps in conjunction pose a significant challenge for delivery of a drug alone or in a dosage form, especially to the posterior segment. Identification of influx transporters on various ocular tissues and designing a transporter-targeted delivery of a parent drug has gathered momentum in recent years. Parallelly, colloidal dosage forms such as nanoparticles, nanomicelles, liposomes, and microemulsions have been widely explored to overcome various static and dynamic barriers. Novel drug delivery strategies such as bioadhesive gels and fibrin sealant-based approaches were developed to sustain drug levels at the target site. Designing noninvasive sustained drug delivery systems and exploring the feasibility of topical application to deliver drugs to the posterior segment may drastically improve drug delivery in the years to come. Current developments in the field of ophthalmic drug delivery promise a significant improvement in overcoming the challenges posed by various anterior and posterior segment diseases