3–4.5 h

Schedule I (Canada)

Schedule II (US)

Schedule 8 (Australia)

Class A (CD)Schedule II (UK)

45%

Moderate–High

B/D (prolonged use or in high doses at term)

oral, intramuscular, intravenous, intranasal, subcutaneous, transdermal, rectal, epidural

Urine (19% unchanged)

Hepatic: primarily CYP3A, secondarily CYP2D6

100% (IV); Up to 87% (oral)

HCl: 166 mg/mL (20°C)