Formulation optimization of a drug in adhesive transdermal analgesic patch

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Pediatric Pharmacology

Background:

• Conventional pain relief methods present challenges like side effects and administration difficulties.
• Transdermal drug delivery offers a promising alternative to overcome these limitations.

Purpose of the Study:

• To formulate a novel drug-in-adhesive transdermal patch containing codeine (CDB) and acetaminophen (APAP) for moderate pain in children.
• To evaluate the permeation profiles of CDB and APAP across various skin models.

Main Methods:

• Screening of analgesic drugs including hydrocodone bitartrate, CDB, and APAP using slide crystallization.
• Permeation studies utilizing vertical Franz diffusion cells across porcine ear skin, human skin, and epidermis.
• Quantification of drug permeation by high-performance liquid chromatography.
• Preparation of transdermal patches by dissolving drugs in adhesive with or without oleic acid (OA).

Main Results:

• Codeine (CDB) exhibited superior permeation (660.21 µg/cm²) and shortest lag time (4.35 h) among the screened drugs.
• Optimal drug concentrations for patch formulation were determined: 40% of saturation solubility (Cs) for CDB and 200% Cs for APAP.
• A CDB-APAP patch with 5% OA delivered 151.40 µg/cm² CDB and 58.12 µg/cm² APAP within 24 hours.

Conclusions:

• Drug-in-adhesive transdermal patches containing CDB and APAP were successfully developed for pediatric use.
• The addition of oleic acid significantly enhanced drug solubility and permeation.
• These patches represent a viable alternative for managing moderate pain in infants and children.