Developing optimal bases for effective transdermal delivery of tramadol in felines for pain relief

Chronic or acute pain, can induce stress and reduce overall quality of life for domestic felines. Tramadol, a synthetic opioid that exerts analgesic effects by binding to μ-opioid receptors as well as inhibiting neuronal reuptake of norepinephrine and serotonin, can be used alone or in combination with NSAIDs for the treatment of domestic feline pain. For felines, transdermal delivery is an optimal route to enhance compliance and treatment outcomes. Tramadol can be incorporated into existing transdermal bases such as PLO or Lipoderm for transdermal delivery. However, commercially available bases may not be ideal as they (1) are not be formulated specifically for cats, (2) may contain chemicals that are incompatible with cats such as benzoic acid and phenolics, (3) can be very expensive. In this study, we propose the formulation of a tramadol loaded transethosome gel for transdermal delivery of tramadol through the inner pinna of the cat’s ear. Transethosomes are lipid nanoparticle formulations which have enhanced transdermal delivery, controlled release properties and are versatile for encapsulating a broad range of drugs. Our formulation will be optimized for transdermal delivery in cats, and formulated to not contain substances incompatible with cats. The proposed feline transethosome formulation will benefit the patients, their owners or caregivers and attract commercial interest from the veterinary and pharmaceutical industries.