Pharmaceutical development and clinical effectiveness of a novel gel technology for transdermal drug delivery

Hydrogel Formulations for Topical Insulin Application: Preparation, Characterization and In Vitro Permeation across the Strat-M® Membrane

Insulin has shown efficacy in the treatment of hard-to-heal wounds, which is mainly due to its role in regulating oxidative stress and inflammatory reactions. The aim of this study was to develop an insulin-hydrogel carrier based on Sepineo™ P 600 and Sepineo™ PHD 100 for application to lesional skin. Preformulation studies of the developed formulations were performed in terms of analysis of the pharmaceutical availability of insulin from the hydrogels through the Strat-M® membrane, and rheological and texture measurements. Insulin is released in a prolonged manner; after a time of 6.5 h, 4.01 IU/cm2 (53.36%) and 3.69 IU/cm2 (47.4%) of the hormone were released from the hydrogel based on Sepineo™ P 600 and Sepineo™ PHD 100, respectively. Rheological analysis showed that the hydrogels tested belong to non-Newtonian, shear-thinning systems with yield stress. The insulin-hydrogel based on Sepineo™ P 600 and Sepineo™ PHD 100 shows optimal application properties. The results obtained provide a basis for further preclinical and clinical studies.

Improved transdermal delivery of valsartan using combinatorial approach of polymeric transdermal hydrogels and solid microneedles: an ex vivo proof of concept investigation

Valsartan (VAL) is used as a first-line agent to treat hypertension. However, VAL exhibits poor absorption and low bioavailability when administrated orally. To overcome these issues, VAL transdermal gel was developed in this study, where Carbopol was used as the gel matrices. Additionally, solid microneedles (Dermaroller^®) with various needle lengths were combined with transdermal gel to improve its permeation across the stratum corneum as a skin barrier. Developed formulations were further evaluated for various parameters, including pH, viscosity, spreadability, extrudability, gel strength, drug content, ex vivo permeation, in vitro release, occlusivity, and hemolysis. The results showed that all formulations exhibited desired physical characteristics without any potential to cause toxicity. Moreover, this approach showed that using microneedles could significantly enhance the permeation of VAL up to 3 folds compared to untreated skin. The use of microneedles 1.5 mm was found to be the optimum combination to improve VA permeation without affecting skin integrity. As much as 1.69 ± 0.004 mg of VAL permeated after 8 h. Finally, it could be concluded that this work had successfully developed a new approach for VALS drug delivery and could potentially show a significant impact on the treatment of hypertension. Further in vivo work should be considered.

Combinatorial Approach of Thermosensitive Hydrogels and Solid Microneedles to Improve Transdermal Delivery of Valsartan: an In Vivo Proof of Concept Study

Due to the limitations of oral administration of valsartan, in this study, we aimed to develop thermosensitive hydrogel for sustained transdermal delivery and improved bioavailability of valsartan, which was further improved using solid microneedles. The thermosensitive gel formula was made using Poloxamer 407 and Poloxamer 188 in various ratios. Valsartan thermosensitive gels were evaluated for their gelation temperature, pH values, drug content, spreadability, viscosity, rheological properties, in vitro drug release, in vitro permeation, and ex vivo permeation. Finally, in vivo study was conducted, compared to oral administration. The results presented the formulations showed required characteristic for transdermal administration with desired thermosensitive properties. Based on the permeation test with and without microneedles, it was found that the use of microneedles could affect the permeation of valsartan. Specifically, the increase of microneedles' needle length also increased valsartan permeation. The combination with the highest permeation was produced by 1.55 mm MNs with the amount of drug permeated of 2.27 ± 0.01 mg. Importantly, the transdermal delivery of valsartan using this combination approach could significantly improve the bioavailability of valsartan in in vivo study. The concentration of poloxamer was able to affect the properties of the hydrogels, and the use of solid microneedles improved the transdermal delivery of valsartan. In vivo studies showed the improvement of the bioavailability of valsartan compared to oral administration, showing the effectiveness of this combination approach.

The Potential of Pharmaceutical Hydrogels in the Formulation of Topical Administration Hormone Drugs

Hormones have attracted considerable interest in recent years due to their potential use in treatment of many diseases. Their ability to have a multidirectional effect leads to searching for new and increasingly effective drugs and therapies. Limitations in formulating drug forms containing hormones are mainly due to their low enzymatic stability, short half-life and limited bioavailability. One of the solutions may be to develop a hydrogel as a potential hormone carrier, for epidermal and transdermal application. This review discusses the main research directions in developing this drug formulation. The factors determining the action of hormones as drugs are presented. An analysis of hydrogel substrates and permeation enhancers that have the potential to enhance the efficacy of hormones applied to the skin is reviewed.

Assessment of estrogen exposure from transdermal estradiol gel therapy with a dried urine assay

Transdermal estradiol gel is a commonly used menopausal hormone therapy. In research studies investigating the pharmacokinetics and clinical utility of transdermal estradiol gels, serum is often used to measure estradiol levels. Serum results only represent a moment in time during phlebotomy and thus provide little information and allow for limited inference unless serial measurements are performed. In contrast, dried urine may provide a representation of serum estradiol levels over a longer period of time, while also being non-invasive and easier to collect. The primary aim of this study was to evaluate a dried urine method to determine if it may be a viable option for evaluating estrogen exposure resulting from transdermal estradiol gel use. A secondary aim was to explore differences in the urinary estrogen profiles of premenopausal women on no therapy and postmenopausal women who were either on transdermal estradiol gel therapy or no therapy at all. The results of this study demonstrated that the expected dose-proportional changes in estrogen exposure can be observed in the urinary estrogen profile using a GC-MS/MS dried urine assay. The GC-MS/MS assay also showed the differences in the urinary estrogen profiles of premenopausal women, postmenopausal women on estrogen replacement therapy, and postmenopausal women on no therapy.

Film-Forming Systems for Dermal Drug Delivery

Film-forming formulations represent a novel form of sustained release dermatic products. They are applied to the skin as a liquid or semi-solid preparation. By evaporation of the volatile solvent on the skin, the polymer contained in the formulation forms a solid film. Various film-forming formulations were tested for their water and abrasion resistance and compared with conventional semi-solid formulations. Penetration and permeation studies of the formulations indicate a potential utility as transdermal therapeutic systems. They can be used as an alternative to patch systems to administer a variety of drugs in a topical way and may provide sustained release characteristics.

Updates on thermosensitive hydrogel for nasal, ocular and cutaneous delivery

Thermosensitive hydrogels are in situ gelling systems composed of hydrophilic homopolymers or block copolymers which remain as solutions at room temperature and form gels after administration into the body. Its application in advanced drug delivery has gained significant attention in recent years. The tunable characteristics of thermosensitive hydrogels make them versatile and capable of incorporating both hydrophilic and lipophilic compounds and macromolecules. The drug molecules can be included as free molecules or preformulated into nano- or micro-particles or liposomes. Although there were several reviews on the materials of thermosensitive hydrogels, the compatibility between the drug and thermosensitive material as well as its in vitro release mechanisms and in vivo performance have barely been investigated. The current review is proposed aiming to not only provide an update on the recent development in thermosensitive hydrogel formulations for nasal, ocular and cutaneous deliveries, but also identify the relationship between the drug characteristics and the loading strategies, and their impacts on the release mechanisms and the in vivo performance. Our current update for the first time highlights the essential features for successful development of in situ thermosensitive hydrogels to facilitate nasal, ocular or cutaneous drug deliveries.

An update on the use of transdermal oxybutynin in the management of overactive bladder disorder

Antimuscarinic medications are used to treat nonneurogenic overactive bladder refractory to nonpharmacologic therapy. Side effects such as dry mouth, constipation, blurred vision, dizziness, and impaired cognition limit the tolerability of therapy and are largely responsible for high discontinuation rates. Oxybutynin is a potent muscarinic receptor antagonist whose primary metabolite after first-pass hepatic metabolism is considered largely responsible for its associated anticholinergic side effects. Transdermal administration of medications bypasses hepatic processing. Specifically with oxybutynin, whose low molecular weight permits transdermal administration, bioavailability of the parent drug with oral administration is less than 10%, whereas with transdermal delivery is a minimum of 80%. The result has been an improved side effect profile in multiple clinical trials with maintained efficacy relative to placebo; however, the drug may still be discontinued by patients due to anticholinergic side effects and application site reactions. Transdermal oxybutynin is available as a patch that is changed every 3-4 days, a gel available in individual sachets, or via a metered-dose pump that is applied daily. The transdermal patch was briefly available as an over-the-counter medication for adult women, although at this time all transdermal formulations are available by prescription only.

Wound healing efficacy of a chitosan-based film-forming gel containing tyrothricin in various rat wound models

The objective of this study was to evaluate the healing effects of a chitosan-based, film-forming gel containing tyrothricin (TYR) in various rat wound models, including burn, abrasion, incision, and excision models. After solidification, the chitosan film layer successfully covered and protected a variety of wounds. Wound size was measured at predetermined timepoints after wound induction, and the effects of the film-forming gel were compared with negative (no treatment) and positive control groups (commercially available sodium fusidate ointment and TYR gel). In burn, abrasion and excision wound models, the film-forming gel enabled significantly better healing from 1 to 6 days after wound induction, compared with the negative control. Importantly, the film-forming gel also enabled significantly better healing compared with the positive control treatments. In the incision wound model, the breaking strength of wound strips from the group treated with the film-forming gel was significantly increased compared with both the negative and positive control groups. Histological studies revealed advanced granulation tissue formation and epithelialization in wounds treated with the film-forming gel. We hypothesize that the superior healing effects of the film-forming gel are due to wound occlusion, conferred by the chitosan film. Our data suggest that this film-forming gel may be useful in treating various wounds, including burn, abrasion, incision and excision wounds.

Pharmacokinetics and bioavailability of a new testosterone gel formulation in comparison to Testogel® in healthy men

This randomized, open-label, multiple-dose three-way cross-over study compared the pharmacokinetics of a new testosterone gel formulation in two strengths, testosterone gel 1% and testosterone gel 2% (FE 999303), with Testogel® in 11 testosterone-suppressed healthy men. Subjects received one of six treatment sequences; 50 mg of testosterone was administered once daily for 7 consecutive days, with different treatments separated by washout-periods of 6-9 days. Testosterone gel 1% and testosterone gel 2% displayed greater relative bioavailability (2.6- and 1.6-fold, respectively) than Testogel on Day 1, which persisted, to a smaller extent, on Day 7. Initial absorption was highest and most rapid for testosterone gel 1% and 2%, showing apparent first-order absorption kinetics. Maximum serum concentrations (Cmax ) were 6.25 and 2.97 ng/mL, respectively, occurring ∼5-6 hours post-application on Day 1 versus Cmax of 1.71 ng/mL after ∼24 hours with Testogel, showing apparent zero-order absorption kinetics. Similar differences were observed on Day 7. All treatments appeared to reach approximately the same steady-state level within the first 24 hours. No application-site skin reactions occurred with any preparation. In conclusion, the new testosterone formulation showed higher bioavailability, and the ability to deliver more testosterone in a smaller volume.

Clinical utility of transdermal delivery of oxybutynin gel via a metered-dose pump in the management of overactive bladder

Oxybutynin is an efficacious treatment for overactive bladder, but its clinical utility is hampered by relative intolerability due to its side effect profile. Over the last few years, various attempts to enhance the tolerability of oxybutynin by varying the drug delivery mechanism have been introduced and have included extended release, rectal suppository, transdermal patch, and gel formulations. The recent introduction of a transdermal oxybutynin gel in a sachet form has been complemented by the administration of gel in a metered dose pump. This paper reviews the available evidence for transdermal oxybutynin gel and, where it exists, for the pump-based gel. The clinical utility of the pump-based gel is discussed.

Pharmacokinetics and toxicity of antimuscarinic drugs for overactive bladder treatment in females

INTRODUCTION

Antimuscarinics (AMs) are the mainstay of pharmacological treatment of overactive bladder (OAB), a symptom complex defined by the presence of urinary urgency, usually associated with frequency and nocturia, with or without urgency urinary incontinence. The AMs used to treat OAB differ in their pharmacological profiles, which may affect their potential for causing adverse effects (AEs).

AREAS COVERED

The present article aims to review the literature about pharmacokinetics (PK) of the different AMs used in the treatment of OAB. Furthermore, the AEs related to the use of these drugs and their incidence are presented. This systematic review is based on material searched and obtained via Medline, Pubmed and EMBASE up to March 2012 using the search terms "adverse events, pharmacokinetics, tolerability" in combination with "darifenacin, fesoterodine, imidafenacin, oxybutynin, propiverine, solifenacin, tolterodine, and trospium."

EXPERT OPINION

Antimuscarinics are the first-line pharmacological treatment for OAB. Despite the development of new molecules that improve their efficacy/safety profile, there are some drugs that are pharmacokinetically more appropriate to be prescribed in specific populations such as patients with neurological disease or the elderly. Moreover, research should be encouraged in evaluating antimuscarinics in conjunction with other drugs such as estrogens or beta-agonists. The identification of prognostic criteria for pharmacological therapy would be helpful.

Oxybutynin gel for the treatment of overactive bladder

INTRODUCTION

Overactive bladder (OAB) is a common condition that has a profound impact on an individual's overall health and quality of life. Muscarinic receptor antagonists are the mainstay of oral pharmacotherapy for OAB. While all of the medications in this class are significantly more effective than placebo, they are also associated with more adverse events that may limit their overall use. Transdermal application of oxybutynin has been shown to avoid first-pass metabolism and, thus, may be associated with fewer antimuscarinic side effects.

AREAS COVERED

This paper reviews the pharmacology of transdermal oxybutynin gel and summarizes the available data regarding this product in the treatment of OAB. It also discusses the role of this product in the OAB treatment armamentarium.

EXPERT OPINION

Oxybutynin transdermal gel has been shown to have significant advantages over placebo, in terms of urgency incontinence episodes, urinary frequency and voided volume in a Phase III study. Application site effects were higher in the gel group, but the incidence of antimuscarinic side effects were lower than those seen with oral preparations. The lower incidence of skin side effects, as compared with the transdermal patch, may confer a theoretical advantage toward the gel product. While promising, unanswered questions remain regarding persistence with treatment after this mode of therapy, and head-to-head comparisons with other antimuscarinics are absent.

Efficacy and safety of the 2% formulation of testosterone topical solution applied to the axillae in androgen-deficient men

OBJECTIVES

Testosterone replacement therapy in hypogonadal men relieves symptoms and restores serum testosterone levels to the physiological range. In this study, we assessed the safety, pharmacokinetics, and efficacy of the 2% formulation of testosterone topical solution applied daily to the axillae.

DESIGN AND PATIENTS

An open-label trial was conducted in testosterone-deficient men who started on a daily dose of 60 mg of testosterone. Dose was adjusted on Days 45 and 90 when necessary to maintain serum testosterone levels within the physiological range (10·41-36·44 nmol/l) based on average serum testosterone levels on Days 15 and 60, respectively. Sexual function and mood changes were assessed by the Psychosexual Daily Questionnaire (PDQ) for the 7 days preceding visits at Days 1, 15, 60, and 120; and quality of life by SF-36 questionnaire on Days 1, 60, and 120. Safety parameters, laboratory tests, and adverse events were collected at each visit.

RESULTS

Among the Completer Set (135 study completers and 3 patients who discontinued due to adverse events), 76·1% (Days 15/16), 84·8% (Days 60/61), and 84·1% (Days 120/121) had an average total testosterone level between 10·41-36·44 nmol/l. PDQ scores increased significantly from baseline to 120 days of treatment (p < 0·0001). Significant improvement was observed in the physical (p < 0·05) and mental (p < 0·0001) components of the SF-36 after 120 days of treatment. Adverse events reported in >2% of the 155 subjects who received ≥ 1 dose were application site irritation (7·1%), application site erythema (5·2%), headache (5·2%), increased hematocrit (3.9%), nasopharyngitis (3·9%), diarrhea (2·6%), and vomiting (2·6%).

CONCLUSIONS

These results indicate that once-daily application of the testosterone topical solution 2% to the axillae is a safe and effective treatment for androgen replacement in hypogonadal men.

Bioadhesive film formed from a novel organic-inorganic hybrid gel for transdermal drug delivery system

A novel organic-inorganic hybrid film-forming agent for TDDS was developed by a modified poly(vinyl alcohol) (PVA) gel using γ-(glycidyloxypropyl)trimethoxysilane (GPTMS) as an inorganic-modifying agent, poly(N-vinyl pyrrolidone) (PVP) as a tackifier and glycerol (GLY) as a plasticizer. The prepared gels can be applied to the skin by a coating method and in situ form very thin and transparent films with good performance, comfortable feel and cosmetic attractiveness. The key properties of the bioadhesive films produced from the hybrid gels were investigated and the results showed that the incorporation of appropriate GPTMS (GPTMS/(PVA+GPTMS) in the range of 20-30%) into the PVA matrix not only can significantly enhance mechanical strength and skin adhesion properties of the resultant film, but also can decrease the crystalline regions of PVA and hence facilitate the diffusion of water vapor and drug. Furthermore, the investigations into in vivo skin irritation suggested the films caused non-irritation to skin after topical application for 120 h. In conclusion, the bioadhesive films formed from organic-inorganic hybrid gels possessed very good qualities for application on the skin and may provide a promising formulation for TDDS, especially when the patient acceptability from an aesthetic perspective of the dosage form is a prime consideration.

Emerging drugs for treatment of overactive bladder and detrusor overactivity

BACKGROUND

Overactive bladder (OAB) signifies the presence of urinary urgency and can have major effects on quality of life and social functioning. Standard antimuscarinic drugs have good initial response rates but substantial adverse effects and long-term compliance problems.

OBJECTIVES

To review the complexities of the mechanisms underlying OAB and the current drugs available for treating its symptoms.

METHODS

The literature was reviewed to define current therapies and drugs in clinical trials. Articles were identified by means of a computerised PubMed and Cochrane Library search (using the following keywords: overactive bladder, detrusor overactivity, urgency and bladder), supported by a search of the PharmaProjects database.

CONCLUSIONS

New drug classes, such as beta-3 adrenergic agonists, may work by reducing contractility or excitability of bladder muscle. Moderation of afferent activity may allow improved OAB symptoms, with lower risk of affecting voiding function. Agents acting on the CNS could influence OAB favourably, but target selection and adverse effects are an issue. The recognition of the functional contribution of the urothelium and the diversity of nerve transmitters has sparked interest in both peripheral and central modulation of OAB pathophysiology.

Testosterone solid lipid microparticles for transdermal drug delivery. Formulation and physicochemical characterization

PURPOSE

The main objective of the study was to formulate and characterize testosterone (TS) solid lipid microparticles (SLM) to be applied as a transdermal delivery system.

METHODS

Testosterone SLMs were formulated using an emulsion melt homogenization method. Various types and concentrations of fatty materials, namely glyceryl monostearate (GM), glyceryl distearate (GD), stearic acid (SA) and glyceryl behanate (GB) were used. The formulations contained 2.5 or 5 mg TS g(-1). Morphology, particle size, entrapment efficiency (EE), rheological properties and thermal behaviour of the prepared SLM were examined. In vitro release characteristics of TS from various prepared SLM were also evaluated over 24 h using a vertical Franz diffusion cell. In addition, the effect of storage and freeze-drying on particle size and release pattern of TS from the selected formulation was evaluated.

RESULTS

The results indicated that the type of lipid affected the morphology and particle size of SLM. A relatively high drug percentage entrapment efficiency ranging from 80.7-95.7% was obtained. Rheological studies showed plastic flow characteristics of the prepared formulations. DSC examination revealed that TS existed in amorphous form in the prepared SLM. Release studies revealed the following rank order of TS permeation through cellophane membrane after application of various formulations: 5% GM < 5% GD < 5% SA < 5% GB < 2.5% GM < 2.5% SA < 10% GD < 10% GB. The drug permeation through excised abdomen rat skin after application of 10% GB-2.5 mg TS g(-1) SLM was lower than that permeated through cellophane membrane. Moreover, SLM containing 10% GB-2.5 mg TS g(-1) stored at 5 degrees C showed good stability as indicated by the release study and particle size analysis. Trehalose showed high potential as a cryoprotectant during freeze drying of the selected SLM formulation.

CONCLUSIONS

The developed TS SLM delivery system seemed to be promising as a TS transdermal delivery system.

Anchoring junctions as drug targets: role in contraceptive development

In multicellular organisms, cell-cell interactions are mediated in part by cell junctions, which underlie tissue architecture. Throughout spermatogenesis, for instance, preleptotene leptotene spermatocytes residing in the basal compartment of the seminiferous epithelium must traverse the blood-testis barrier to enter the adluminal compartment for continued development. At the same time, germ cells must also remain attached to Sertoli cells, and numerous studies have reported extensive restructuring at the Sertoli-Sertoli and Sertoli-germ cell interface during germ cell movement across the seminiferous epithelium. Furthermore, the proteins and signaling cascades that regulate adhesion between testicular cells have been largely delineated. These findings have unveiled a number of potential "druggable" targets that can be used to induce premature release of germ cells from the seminiferous epithelium, resulting in transient infertility. Herein, we discuss a novel approach with the aim of developing a nonhormonal male contraceptive for future human use, one that involves perturbing adhesion between Sertoli and germ cells in the testis.

Transdermal oxybutynin in the treatment of overactive bladder

Overactive bladder is a dreadful syndrome that affects a considerable number of patients. Antimuscarinics are the mainstay of pharmacotherapy for this condition. Transdermal (TD) oxybutynin (OXY) bypasses the first-pass metabolism and reduces the formation of N-desethyloxybutynin, a compound believed to be associated with anticholinergic side effects. The 3.9 mg matrix TD system is applied twice weekly and transports OXY directly into the systemic circulation. The patch can be applied to abdomen, buttock, and hip, and provides continuous OXY delivery that minimizes peak and trough fluctuations in plasma levels. In clinical trials, TD and oral OXY produced a significant reduction in incontinence episodes, with no difference between oral and TD treatments. In addition, TDOXY was similar to tolterodine, and it produced a significant improvement in the number of urinary incontinence episodes, complete continence, and urodynamic and quality of life parameters compared with placebo. The incidence of anticholinergic adverse events with TDOXY was similar to placebo. Most common adverse events were mild–moderate skin reactions. Treatment satisfaction survey suggested patients’ preference to use the TD system in the future. Counseling on healthy skin care and appropriate product use can enhance patients’ knowledge about TDOXY for overactive bladder treatment.

Chapitre C-l A - Traitement pharmacologique de l’hyperactivité détrusorienne neurologique : per os, en patch, en instillation endo-vésicale

Functional rehabilitation of neurourological patients always starts with patient education, retraining, and occupational therapy, possibly completed by medical treatments. In the light of a systematic review of the literature, the authors describe the various treatments that can be used orally and by intravesical instillation in these patients. They also describe treatments such as desmopressin or agents that increase sphincter pressure, which can sometimes be very useful to obtain stable clinical results that are satisfactory for the patient.