Topical NSAIDs for acute local pain relief: in vitro characterization of drug delivery profiles into and through human skin

Osteoarthritis: Insights into Diagnosis, Pathophysiology, Therapeutic Avenues, and the Potential of Natural Extracts

Osteoarthritis (OA) stands as a prevalent and progressively debilitating clinical condition globally, impacting joint structures and leading to their gradual deterioration through inflammatory mechanisms. While both non-modifiable and modifiable factors contribute to its onset, numerous aspects of OA pathophysiology remain elusive despite considerable research strides. Presently, diagnosis heavily relies on clinician expertise and meticulous differential diagnosis to exclude other joint-affecting conditions. Therapeutic approaches for OA predominantly focus on patient education for self-management alongside tailored exercise regimens, often complemented by various pharmacological interventions primarily targeting pain alleviation. However, pharmacological treatments typically exhibit short-term efficacy and local and/or systemic side effects, with prosthetic surgery being the ultimate resolution in severe cases. Thus, exploring the potential integration or substitution of conventional drug therapies with natural compounds and extracts emerges as a promising frontier in enhancing OA management. These alternatives offer improved safety profiles and possess the potential to target specific dysregulated pathways implicated in OA pathogenesis, thereby presenting a holistic approach to address the condition's complexities.

Testing Topical Products Specifically to Reduce Inflammatory Pain from Gout: Transdermal NSAID Delivery and Monosodium Urate Solubility

Purpose

Gout is caused by crystals of monosodium urate (MSU) in the joints. Topical nonsteroidal anti-inflammatory drug products (NSAIDs) are often the first-choice immediate treatment. This study examined the effect of commercially available and newly developed transdermal NSAID products on the solubility of MSU in a physiologically relevant system, alongside the efficacy of transdermal NSAID delivery.

Materials and Methods

Drug permeability of 7 commercially available topical NSAID products, alongside 3 newly developed “Gout Buster” products, was evaluated in vitro using pig’s ear skin in Franz diffusion cells. The standard Franz cell experimental protocol was adapted to include assessment of MSU solubility in phosphate buffered saline for each product. Some materials were also tested via direct solubility studies.

Results

The amount of drug delivered transdermally varied significantly between different formulations, with the best ibuprofen delivery being ~5 times higher than the lowest, and best diclofenac delivery being ~3.5 times higher than the lowest. Changes in formulations and the drug concentration in the product both affected the amount of drug delivered. Overall ibuprofen permeation was higher than diclofenac. The commercially available products showed little or no effect on the MSU solubility (99–103% vs control). The Gout Buster products showed significant improvement in the MSU solubility after permeation through skin (120–126%). Increased sodium levels reduced the solubility of MSU in direct solubility studies.

Conclusion

In these trials, the Gout Buster products showed significantly improved permeation of both ibuprofen and diclofenac over the commercial products at similar drug concentrations, and showed significant improvement for MSU solubility. Increased sodium levels reduced the solubility of MSU and could cause more crystallisation in vivo. Therefore, topical NSAID products with the Gout Buster formulation may have the best likelihood of both reducing inflammation and helping re-dissolve the MSU crystals that cause gout.

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