SUBUTEX (buprenorphine) sublingual tablet is an uncoated oval white flat beveled edged tablet, debossed with an alphanumeric word identifying the product and strength on one side. It contains buprenorphine HCl, a partial agonist at the mu-opioid receptor. It is available in two dosage strengths, 2 mg buprenorphine and 8 mg buprenorphine (as the free base, equivalent to 2.16 mg buprenorphine hydrochloride USP and 8.64 mg buprenorphine hydrochloride USP). Each tablet also contains lactose, mannitol, cornstarch, povidone K30, citric acid, sodium citrate, and magnesium stearate.