Pharmacokinetic profile of a new matrix-type transdermal delivery system: diclofenac diethyl ammonium patch

Enhanced delivery of diclofenac diethylamine loaded Eudragit RL 100® transdermal system against inflammation

A transdermal therapeutic system (TTS) of diclofenac diethylamine (DDE) was developed to obtain a prolonged controlled drug delivery by the solvent evaporation technique. The matrix diffusion controlled systems used various combinations of hydrophilic (polyvinylpyrrolidone K30) and lipophilic (Eudragit RL 100® and Eudragit RS 100®) polymers containing dimethyl sulfoxide (DMSO) (0, 5 and 10% w/w) as a penetration enhancer. In vitro drug release was improved with an increased fraction of hydrophilic polymer. Formulation F8 containing Eudragit RL 100® and polyvinylpyrrolidone K30 in the ratio 40:60 presented the highest drug release (92.45%) and permeation rate (0.0988±0.010 mg/cm2/h) with sustained release action for 48 h. In vivo pharmacodynamic study of DDE-loaded Eudragit RL 100® transdermal system (formulation F8) showed significant higher percent inhibition of rat paw edema compared with the marketed formulation of the drug. Our results suggest that a developed formulation is an efficient system for transdermal diclofenac delivery against inflammation. The optimized formulation was found to be stable and did not show physicochemical interaction. The system is envisaged to be stable for a sufficiently long period (2.52 years) at room temperature.

Transdermal diclofenac patches for control of post-extraction pain. Pilot randomized controlled double-blind study

PURPOSE

The scope of transdermal analgesics have been limited to pain control following local trauma, muscle spasm, minor esthetic surgeries, or sports-related injuries. Its scope of application can be extended in the field of dentistry and minor oral surgical procedures.

METHODS

A total of 40 healthy patients between the age of 18 and 50 years with deeply carious, nontender mandibular molar tooth deemed unsalvageable which was indicated for extraction were taken into study of which subjects were divided into cases and controls.

RESULTS

The data were analyzed with chi-square test and Mann-Whitney U test; the chi-square test showed significant association with expected outcome in visual analog scale pain scores, the two groups at 6th and 12th hour. A Mann-Whitney U test was performed to identify strength of association between two groups where there were significant association between all parameters except for pain interference with routine activities and dental health status(0.022, 0.001); the differences between two groups in these parameters were significant (<0.05).

CONCLUSION

Transdermal route seems to be comparable to oral diclofenac in post-extraction pain relief; further studies are required to confirm the results and safety for its use in various other dental situations.

Ketorolac trometamol topical formulations: release behaviour, physical characterization, skin permeation, efficacy and gastric safety

Objectives

The objective of this study was to improve systemic delivery of the highly analgesic ketorolac trometamol (ketorolac tromethamine) via the transdermal route, through cost-effective topical formulations, to avoid most of the problems associated with ketorolac trometamol therapy.

Methods

In-vitro release behaviour of the drug from different microemulsion and emulgel formulations was evaluated. E2 emulgel (based on isopropyl myristate as penetration enhancer) and E7 emulgel (based on Brij 92 as penetration enhancer) were evaluated for their physical properties, rat skin permeation, in-vivo analgesic effect (hot-plate test and the paw pressure test), acute and chronic anti-inflammatory activity and gastric safety.

Key findings

Isopropyl myristate and the synergistic effect of the two known penetration enhancers (propylene glycol and Brij 92) significantly modulated drug permeation and may be a promising approach for the transdermal delivery of ketorolac trometamol and other drugs. Selected in-vivo tested formulae (E2 and E7) caused significantly less ulcer score and less gastric erosion compared with oral ketorolac trometamol. E7 showed significantly higher analgesic and anti-inflammatory activity compared with E2 with no significant difference compared with oral ketorolac trometamol.

Conclusions

The developed ketorolac trometamol E7 emulgel appeared promising for dermal and transdermal delivery of ketorolac trometamol, which would circumvent most of the problems associated with drug therapy.

Ex Vivo Study of Transdermal Permeation of Four Diclofenac Salts from Different Vehicles

The ex vivo permeation of diclofenac was studied using four different salts (sodium, potassium, diethylamine, and epolamine) dissolved in four different solvents (water, propylene glycol (PG), Transcutol, and oleic acid (OA)) as donor phases through a human skin membrane. The four salts show different solubility values and different behavior in the four solvents, which are also permeation enhancers and this fact further is connected to the permeation results. The same order of magnitude of fluxes through the membrane as those previously reported for acidic diclofenac released from buffer solutions of pH >7 were found, taking into account differences originated by different membranes and other parameters tested in the experiments. Saturation concentration for the four salts in different solvents, necessary to calculate permeation coefficients, was critically evaluated; a short discussion made it possible to explain that corrections in the solubility values must be considered, related to the complex behavior in solution of these salts. Statistical processing of the experimental data suggests that differences between the four salts in promoting absorption of the drug is unproven; while differences are evident between the solvents, water is the most effective enhancing vehicle. Aqueous formulations containing diclofenac salt with an organic base appear to be the best combination to promote permeation in topical applications.

Design and evaluation of matrix diffusion controlled transdermal patches of verapamil hydrochloride

Transdermal patches of verapamil hydrochloride were prepared using four different polymers (individual and combination): Eudragit RL100 (ERL100), Eudragit RS100 (ERS100), hydroxypropyl methylcellulose 15 cps (HPMC), and ethyl cellulose (EC), of varying degrees of hydrophilicity and hydrophobicity. The effect of the polymers on the technological properties, i.e., drug release, water vapor transmission rate (WVTR), and percentage moisture loss (ML), percentage moisture absorption (MA), folding endurance, and thickness, was investigated. Different formulations were prepared in accordance with the 2(3) factorial design, with ERL100 being the parent polymer. The patch containing ERL100 alone showed maximum WVTR, % MA, and % ML, which could be attributed to its hydrophilic nature. As expected, substitution with ERS100, HPMC, and EC decreased all the above values in accordance with their decreasing degree of hydrophilicity. In vitro release studies showed zero-order release of the drug from all the patches, and the mechanism of release was diffusion mediated. Moreover, the release of the drug was sustained and it extended over a period of 24 hr in all formulations. A12 emerged as the most satisfactory formulation insofar as its technological properties were concerned. Further, release and permeation of the drug from the most satisfactory formulation (A12) was evaluated through different biological barriers (shed snake skin, rabbit skin, and rat skin) to get an idea of the drug permeation through human skin. Shed snake's skin was found to be most permeable (82.56% drug release at 24 hr) and rat skin was least permeable (52.38%). Percutaneous absorption studies were carried out in rabbits. The pharmacokinetic parameters calculated from blood levels of the drug revealed a profile typical of a sustained release formulation, with the ability to maintain adequate plasma levels for 24 hr. [AUC: 3.09 mg/mL hr, Cmax: 203.95 microg/mL, Tmax: 8 hr]. It can therefore be concluded that the patch containing ERL100 and HPMC in the ratio 8:2 has achieved the objectives of transdermal drug delivery system, such as avoidance of first pass effect, extended release, and reduced frequency of administration.

Design, development, physicochemical, and in vitro and in vivo evaluation of transdermal patches containing diclofenac diethylammonium salt

In this study, matrix-type transdermal patches containing diclofenac diethylamine were prepared using different ratios of polyvinylpyrrolidone (PVP) and ethylcellulose (EC) by solvent evaporation technique. The drug matrix film of PVP and EC was casted on a polyvinylalcohol backing membrane. All the prepared formulations were subjected to physical studies (moisture content, moisture uptake, and flatness), in vitro release studies and in vitro skin permeation studies. In vitro permeation studies were performed across cadaver skin using a modified diffusion cell. Variations in drug release profiles among the formulations studied were observed. Based on a physicochemical and in vitro skin permeation study, formulation PA4 (PVP/EC, 1:2) and PA5 (PVP/EC, 1:5) were chosen for further in vivo experiments. The antiinflammatory effect and a sustaining action of diclofenac diethylamine from the two transdermal patches selected were studied by inducing paw edema in rats with 1% w/v carrageenan solution. When the patches were applied half an hour before the subplantar injection of carrageenan in the hind paw of male Wistar rats, it was observed that formulation PA4 produced 100% inhibition of paw edema in rats 12 h after carrageenan insult, whereas in the case of formulation PA5, 4% mean paw edema was obtained half an hour after the carrageenan injection and the value became 19.23% 12 h after the carrageenan insult. The efficacy of transdermal patches was also compared with the marketed Voveran gel and it was found that PA4 transdermal patches produced a better result as compared with the Voveran gel. Hence, it can be reasonably concluded that diclofenac diethylamine can be formulated into the transdermal matrix type patches to sustain its release characteristics and the polymeric composition (PVP/EC, 1:2) was found to be the best choice for manufacturing transdermal patches of diclofenac diethylamine among the formulations studied.

In vitro release study of verapamil hydrochloride through sodium alginate interpenetrating monolithic membranes

Polymeric sodium alginate interpenetrating network membranes containing verapamil hydrochloride were fabricated for transdermal application. The membranes were evaluated for their physical properties, weight and thickness uniformity, water vapor transmission, as well as drug content uniformity. All the thin patches were transparent, smooth, and flexible. The drug-loaded membranes were analyzed by X-ray diffraction to understand the drug polymorphism inside the membrane. The transdermal patches were permeable to water vapor, indicating the permeability characteristics of the polymers. The in vitro drug release was performed in distilled water using a Keshary-Chien diffusion cell. The release data were analyzed to understand the mechanism of drug release.