Effect of O-acylmenthol and salt formation on the skin permeation of diclofenac acid

Development of a Novel Simple Gel Formulation Containing an Ion-Pair Complex of Diclofenac and Phenylephrine

BACKGROUND AND AIM

Since the pharmacological effects of diclofenac (DF) are short-lived because of its short half-life, prolongation of the pharmacological effect in a topical formulation is needed for more appropriate clinical use. For the enhancement of dermal accumulation and prolongation of the pharmacological effect of drugs, the aim of this study was to develop a simple gel formulation containing an ion-pair complex of DF and phenylephrine (PHE), which induce constriction of the vascular smooth muscles.

MATERIALS AND METHODS

The ion-pair complex was prepared by mixing sodium DF and an ethanolic solution of PHE. The formed complex was characterized by powder X-ray diffraction (PXRD) and Fourier-transform infrared (FT-IR) spectroscopy. The ion-pair complex for the gel formulation was prepared by mixing an equimolar concentration of 50% 1,3-butylene glycol and distilled aqueous solution of 2% xanthan gum, which was characterized by proton nuclear magnetic resonance (1H-NMR). Skin permeation and accumulation of DF and PHE were evaluated by in vitro and in vivo studies.

RESULTS

From the results of PXRD and FT-IR, it was suggested that new crystalline peaks formed by the ion-pair complex and their complex interacted with the carboxyl group in DF and the amino group in PHE. In the gel formulation, the ion-pair complexes were detected by 1H-NMR. The ion-pair complex enhanced the accumulation of DF in the skin in the in vitro study. On the other hand, PHE accumulation in the dermis increased with the ion-pair complex, as exhibited by the in vivo study.

CONCLUSION

A new gel formulation containing the ion-pair complex of DF and PHE was developed, which improved the accumulation of DF in skin.

Efficacy and safety of topical diclofenac/menthol gel for ankle sprain: A randomized, double-blind, placebo- and active-controlled trial

Purpose

This study was performed to evaluate topical 1% diclofenac/3% menthol gel in treating ankle sprain.

Design

In this randomized, double-blind, placebo-controlled trial, adolescents and adults with acute ankle sprain (N = 385) applied 4 g of gel containing 1% diclofenac/3% menthol (n = 117), 1% diclofenac (n = 112), 3% menthol (n = 77), or placebo (n = 75) four times daily. The primary outcome was the area under the curve of pain intensity (PI) on movement [0 (no pain) to 10 (extreme pain)] from 24 to 72 hours post-application (AUC_{1–3 days}). Secondary outcomes included pain relief (PR); PI; time to onset of PR, meaningful PR, cooling, and complete recovery; PI difference; sum of PI difference; total PR; reduction in ankle swelling; and the patient’s global assessment of response to treatment.

Results

There were no statistically significant differences in AUC_1–3 between 1% diclofenac/3% menthol and placebo, diclofenac, or menthol gels and no meaningful advantages of 1% diclofenac/3% menthol for any secondary outcome. There was a higher incidence of skin and application-site events with 1% diclofenac/3% menthol than with placebo or 1% diclofenac.

Conclusion

No significant improvement was observed with topical 1% diclofenac/3% menthol gel compared with placebo, 1% diclofenac, or 3% menthol gel in treating pain from ankle sprain.

ClinicalTrials.Gov Identifier: NCT02100670

Microsponges based novel drug delivery system for augmented arthritis therapy

The motive behind present work was to formulate and evaluate gel containing microsponges of diclofenac diethylamine to provide prolonged release for proficient arthritis therapy. Quasi-emulsion solvent diffusion method was implied using Eudragit RS-100 and microsponges with varied drug–polymer ratios were prepared. For the sake of optimization, diverse factors affecting microparticles physical properties were too investigated. Microsponges were characterized by SEM, DSC, FT-IR, XRPD and particle size analysis, and evaluated for morphology, drug loading, in vitro drug release and ex vivo diffusion as well. There were no chemical interactions between drug and polymers used as revealed by compatibility studies outcomes. The drug polymer ratio reflected notable effect on drug content, encapsulation efficiency and particle size. SEM results revealed spherical microsponges with porous surface, and had 7.21 μm mean particle size. The microsponges were then incorporated in gel; which exhibited viscous modulus along with pseudoplastic behavior. In vitro drug release results depicted that microsponges with 1:2 drug–polymer ratio were more efficient to give extended drug release of 75.88% at the end of 8 h; while conventional formulation get exhausted incredibly earlier by releasing 81.11% drug at the end of 4 h only. Thus the formulated microsponge-based gel of diclofenac diethylamine would be a promising alternative to conventional therapy for safer and efficient treatment of arthritis and musculoskeletal disorders.

An explanation for the difference in the percutaneous penetration behavior of tamsulosin induced by two different O-acylmenthol derivatives

Using tamsulosin (TAL) as a model drug, the aim of this study was to investigate and compare the percutaneous permeation behavior of two menthol derivatives, 2-isopropyl-5-methylcyclohexyl heptanoate (M-HEP) and 2-isopropyl-5-methylcyclohexyl decanoate (M-DEC). In vitro transdermal permeation study was carried out using porcine skin. The residual amount of enhancers in the skin after permeation experiment was determined by gas chromatographic (GC) method. The penetration depths of fluorescein were visualized by two-photon confocal laser scanning microscopy (2P-LSM) after the skin being treated with different enhancers. Furthermore, changes in the stretching frequency of functional group of ceramide were investigated by using attenuated total reflectance Fourier transform infrared (ATR-FTIR) technique. After M-HEP addition, the cumulative amount of TAL permeated in 8 h (Q8) reached 20.57±0.54 μg/cm2 and the depth of fluorescein was 40 μm; the CH2 of ceramide symmetric stretching frequency was 4 cm−1 blue shifted. However, M-DEC has an opposite effect on TAL permeation compared with that of M-HEP. TAL is a crucial factor affecting permeation procedure, and microenvironment of lipid region determines promotion capability of the enhancers.

Design of biorelevant test setups for the prediction of diclofenac in vivo features after oral administration

PURPOSE

Design of biorelevant test setups mimicking the physiological conditions experienced by drugs after oral administration along the passage through the mouth and the GI tract for the in vitro evaluation of diclofenac exhibiting multiple-peak phenomenon during absorption.

METHODS

The biorelevant models simulated successively saliva (SSF, pH 6.2-6.75-7.4, 5 mL, 3 min), gastric (SGF-FaSSGF, pH 1.2-1.6, 50-250 mL, 30 min) and intestinal (FaSSIF, pH 6.8, 250 mL, 60 min) fluids. Applying these models, diclofenac free acid and its sodium/potassium salt were comparatively evaluated for dissolution and further characterized by HPLC, optical morphogranulometry, DSC and PXRD to elucidate peculiar behaviors.

RESULTS

Diclofenac salts almost completely dissolved in SSF and showed a transitional dissolution pattern before complete precipitation in SGF/FaSSGF. This peculiar pattern correlated with simultaneous chemical modification and formation of agglomerates. With low dissolution in SSF and almost immediately complete precipitation, these behaviors were not observed with diclofenac free acid. Distinct diclofenac features were strongly determined by pH-modifications after oral administration.

CONCLUSIONS

The multiple-peak phenomenon observed after administrating a solution, suspension or dispersible formulation of diclofenac salts are likely caused by drug precipitation and agglomeration in the stomach leading to irregular gastric-emptying. Diclofenac free acid may provide more reliable in vivo features.