The role of transdermal buprenorphine in the treatment of chronic pain in elderly patients

Abstract

Buprenorphine is a synthetic opioid with partially agonist effects on μ (MOR) receptors and slightly less internal activity compared to morphine. Buprenorphine binds with κ1 (KOR 1), κ2 (KOR 2), δ (DOR) receptors and with ORL–1 (orphan–related ligand–1, NOR) receptors. The drug is absorbed after transmucosal (approximately 30–50%) and transdermal (biological bioavailability equals approximately 50%) route of administration due to significant lipophilicity. Buprenorphine concentration in plasma slowly increases after transdermal patch application reaching minimal effective concentrations after approximately 12–24 h and maximal concentrations of the drug in the serum after approximately 60–80 h. The drug is metabolized in the liver, mainly through CYP3A4 to an active metabolite – norbuprenorphine. Both buprenorphine and norbuprenorphine undergo subsequently glucuronidation through conjugates and in this forms are excreted with the bile. The majority of the drug is excreted with the stool in the form of unbound buprenorphine or norbuprenorphine with 10–30% of the drug excreted with the urine. Buprenorphine metabolism causes that the risk of pharmacokinetic drug interactions is low. Moreover, buprenorphine is safe drug in patients with renal impairment. Mild and moderate hepatic impairment do not significantly influence buprenorphine pharmacokinetics. In this paper a review of buprenorphine clinical studies (with randomization and nonrandomized) conducted in elderly patients was undertaken. Buprenorphine administered in patches by the transdermal is frequently used in the treatment of chronic pain in cancer patients and in the course of other diseases. Buprenorphine may be used successfully in the treatment of neuropathic pain. Buprenorphine administered by transdermal route is preferred opioid analgesic in elderly patients with moderate to severe chronic pain due to beneficial pharmacodynamics and pharmacokinetics