Aipexin

Absorption

After administration of Aipexin topical solution (40 mg/knee every 12 h; total daily diclofenac exposure: 80 mg/knee) for 7.5 days, the mean (SD) AUC0-12 and mean (SD) Cmax were 77.27 (49.89) ng•h/mL and 12.16 (7.66) ng/mL, respectively, on Day 1; and 204.58 (111.02) ng•h/mL and 25.24 (12.95) ng/mL, respectively, at steady state on Day 8. After administration of Aipexin 1.5% topical solution (19.3 mg/knee every 6 h; total daily diclofenac exposure 77.2 mg/knee), the mean (SD) AUC0-12 and mean (SD) Cmax were 27.46 (23.97) ng•h/mL and 2.30 (2.02) ng/mL, respectively, on Day 1; and 141.49 (92.47) ng•h/mL and 17.04 (11.28) ng/mL, respectively, at steady state on Day 8.

The pharmacokinetics and effect of Aipexin were not evaluated under the conditions of heat application, occlusive dressings overlay, or exercise following product application. Therefore, concurrent use of Aipexin under these conditions is not recommended.

Distribution

Diclofenac is more than 99% bound to human serum proteins, primarily to albumin.

Diclofenac diffuses into and out of the synovial fluid. Diffusion into the joint occurs when plasma levels are higher than those in the synovial fluid, after which the process reverses and synovial fluid levels are higher than plasma levels. It is not known whether diffusion into the joint plays a role in the effectiveness of diclofenac.

Elimination

Metabolism

Five diclofenac metabolites have been identified in human plasma and urine. The metabolites include 4'-hydroxy-, 5hydroxy-, 3'-hydroxy-, 4',5-dihydroxy- and 3'-hydroxy-4'-methoxy diclofenac. The major diclofenac metabolite, 4'hydroxy-diclofenac, has very weak pharmacologic activity. The formation of 4'-hydroxy diclofenac is primarily mediated by CYP2C9. Both diclofenac and its oxidative metabolites undergo glucuronidation or sulfation followed by biliary excretion. Acylglucuronidation mediated by UGT2B7 and oxidation mediated by CYP2C8 may also play a role in diclofenac metabolism. CYP3A4 is responsible for the formation of minor metabolites, 5-hydroxy and 3'-hydroxydiclofenac.

Excretion

Diclofenac is eliminated through metabolism and subsequent urinary and biliary excretion of the glucuronide and the sulfate conjugates of the metabolites.

Little or no free unchanged diclofenac is excreted in the urine.

• R52.1 – Chronic intractable pain
• R52.2 – Other chronic pain
• R52.9 – Unspecified pain

Adverse reactions possible when combined with:

• Benzodiazepines

• CNS depressants

• Antidepressants

• MAO inhibitors

Not applicable.