Recent Phase I studies have demonstrated that topical diclofenac diethylamine (DDEA) gels effectively alleviate pain while maintaining significantly lower systemic concentrations compared to oral diclofenac tablets. This advancement in pain management offers a promising alternative for individuals seeking targeted relief with reduced systemic side effects.
Study Design and Methodology
Two randomized, open-label, multiple-dose, crossover Phase I trials were conducted involving healthy volunteers to evaluate the systemic bioavailability of DDEA gels versus oral diclofenac tablets. In the first study, participants applied a 2.32% DDEA gel twice daily, with and without a semiocclusive bandage, or a 1.16% gel four times daily to one ankle. The second study involved applying the 2.32% gel twice daily to either one knee or both knees. Oral diclofenac sodium tablets at a dosage of 50 mg three times daily served as the comparison treatment in both studies.
Key Findings and Bioavailability
The results indicated that the bioavailability of diclofenac from the DDEA 1.16% gel applied four times daily was similar to that of the 2.32% gel applied twice daily, regardless of the use of a bandage. Additionally, in the second study, bioavailability increased proportionally with the number of application sites. Notably, the systemic diclofenac concentration from topical application was up to 150- and 75-fold lower than that from oral treatments, underscoring the reduced systemic exposure.
- DDEA gels achieve comparable pain relief with significantly reduced systemic absorption.
- Application frequency and the number of treatment sites directly influence diclofenac bioavailability.
- The use of a semiocclusive bandage has minimal effect on systemic drug levels.
- Topical formulations present a safer profile with fewer systemic side effects than oral administration.
The conducted studies reinforce the benefit-risk profile of topical DDEA gels, highlighting their potential as a viable option for pain management with minimized systemic drug exposure. Healthcare providers can consider these findings when recommending pain relief strategies, especially for patients concerned about the systemic effects of oral NSAIDs.
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