Is Butrans Patch Buprenorphine HCl?
Yes, the Butrans (buprenorphine) transdermal patch contains buprenorphine hydrochloride (HCl) as its active pharmaceutical ingredient. 1
Chemical Formulation
The FDA drug label explicitly states that each mL of transdermal buprenorphine solution contains 20 mg buprenorphine administered as 21.56 mg of buprenorphine hydrochloride. 1
The molecular formula is C29H41NO4 •HCl with a molecular weight of 504.10, confirming the hydrochloride salt formulation. 1
Buprenorphine HCl is a semi-synthetic opioid analgesic chemically derived from thebaine and classified as a Schedule III controlled substance. 1
Clinical Formulation Details
Butrans is specifically formulated as a transdermal patch delivering 5,10, or 20 mcg/hour of buprenorphine continuously over a 7-day period. 2, 3
The transdermal system provides sustained and consistent steady-state plasma levels, with steady state reached within 48 hours of the first patch application. 3
Inactive ingredients in the formulation include dehydrated alcohol, padimate O, butylated hydroxyanisole, and butylated hydroxytoluene. 1
Pharmacological Properties
Buprenorphine functions as a partial mu-opioid receptor agonist with high binding affinity and slow dissociation, providing prolonged analgesia. 4, 5
The transdermal formulation bypasses first-pass hepatic metabolism (which accounts for 90% metabolism with sublingual forms), potentially providing superior analgesia compared to oral formulations. 4, 5
The partial agonist properties create a ceiling effect for respiratory depression, making it safer than full opioid agonists while maintaining analgesic efficacy. 5, 6