Sublingual Buprenorphine/Naloxone Film in Unanesthetized Rats: Feasibility, Tolerability, and Plasma Exposure

Sublingual buprenorphine/naloxone film in unanesthetized male Sprague-Dawley rats delivered buprenorphine plasma levels peaking at 4.0 ng/mL at 2 h and 0.9 ng/mL at 24 h.

• Why it matters: Preclinical rodent dosing often uses routes that do not match clinical sublingual administration, limiting route-matched tests of buprenorphine pharmacology and opioid-related behavior.
• What they did: Rats received once-daily film delivering 3.2 mg/kg buprenorphine; plasma buprenorphine was quantified by LC-MS/MS after a single dose, and liver outcomes were assessed after 21 days.
• The result: Buprenorphine exposure (AUC(0-24h) = 39.0 h ng/mL) spanned patient therapeutic concentrations, and repeat dosing reduced liver weight without changing serum AST, ALT, ALP, or liver histology.

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