A method of treating pain, e.g., acute post-operative pain, by administering to a
human patient(s) a therapeutically effective
dose of
tramadol intravenously in a
dosing regimen which includes one or more loading doses administered at shortened intervals as compared to dosing at steady-state is disclosed. In certain embodiments, the
dose of
tramadol is from about 45 mg to about 80 mg and the second (and optionally) third doses are intravenously administered at intervals of from about 2 to about 3 hours, and thereafter the
tramadol is intravenously administered at a
dosing interval of about 4 to about 6 hours, until the patient no longer requires treatment with tramadol. In preferred embodiments, the intravenous
dosing regimen provides a Cmax and AUC of tramadol is similar to the Cmax and AUC of an
oral dose of 100 mg
tramadol HCl given every 6 hours. In certain preferred embodiments, the
dosing regimen comprises 50 mg IV tramadol at Hour 0, followed by 50 mg at Hour 2, 50 mg at hour 4, and 50 mg every 4 hours thereafter (e.g., until the patient no longer requires treatment with tramadol).