Absorption

The analgesic activity of Hydromorphone Hydrochloride is due to the parent drug, hydromorphone. Hydromorphone is rapidly absorbed from the gastrointestinal tract after oral administration and undergoes extensive first-pass metabolism. Exposure of hydromorphone (Cmax and AUC0-24) is dose-proportional at a dose range of 2 and 8 mg. In vivo bioavailability following single-dose administration of the 8 mg tablet is approximately 24% (coefficient of variation 21%). Bioequivalence between the Hydromorphone Hydrochloride 8 mg TABLET and an equivalent dose of Hydromorphone Hydrochloride Oral Solution has been demonstrated.

After oral administration of Hydromorphone Hydrochloride, peak plasma hydromorphone concentrations are generally attained within ½ to 1 hour.

Food Effects: In a study conducted with a single 8 mg dose of hydromorphone (2 mg hydromorphone immediate-release tablets), food lowered Cmax by 25%, prolonged Tmax by 0.8 hour, and increased AUC by 35%. The effects may not be clinically relevant.

Distribution

At therapeutic plasma levels, hydromorphone is approximately 8% to 19% bound to plasma proteins. After an intravenous bolus dose, the steady state of volume distribution [mean (% cv)] is 302.9 (32%) liters.

Elimination

The systemic clearance is approximately 1.96 (20%) liters/minute. The terminal elimination half-life of hydromorphone after an intravenous dose is about 2.3 hours.

Metabolism: Hydromorphone is extensively metabolized via glucuronidation in the liver, with greater than 95% of the dose metabolized to hydromorphone-3-glucuronide along with minor amounts of 6-hydroxy reduction metabolites.

Excretion: Only a small amount of the hydromorphone dose is excreted unchanged in the urine. Most of the dose is excreted as hydromorphone-3-glucuronide along with minor amounts of 6-hydroxy reduction metabolites.

Specific Populations

Hepatic Impairment: After oral administration of a single 4 mg dose (2 mg hydromorphone immediate-release tablets), mean exposure to hydromorphone (Cmax and AUC∞) is increased 4-fold in patients with moderate (Child-Pugh Group B) hepatic impairment compared with subjects with normal hepatic function. Due to increased exposure of hydromorphone, patients with moderate hepatic impairment should be started at a lower dose and closely monitored during dose titration. Pharmacokinetics of hydromorphone in severe hepatic impairment patients has not been studied. Further increase in Cmax and AUC of hydromorphone in this group is expected. As such, starting dose should be even more conservative [see Use in Specific Populations (8.6)].

Renal Impairment: After oral administration of a single 4 mg dose (2 mg hydromorphone immediate-release tablets), exposure to hydromorphone (Cmax and AUC0-48) is increased in patients with impaired renal function by 2-fold in moderate (CLcr = 40 to 60 mL/min) and 3-fold in severe (CLcr< 30 mL/min) renal impairment compared with normal subjects (CLcr > 80 mL/min). In addition, in patients with severe renal impairment hydromorphone appeared to be more slowly eliminated with longer terminal elimination half-life (40 hr) compared to patients with normal renal function (15 hr). Patients with moderate renal impairment should be started on a lower dose. Starting doses for patients with severe renal impairment should be even lower. Patients with renal impairment should be closely monitored during dose titration [see Use in Specific Populations (8.7)].

Age: Geriatric Population:In the geriatric population, age has no effect on the pharmacokinetics of hydromorphone.

Sex: Sex has little effect on the pharmacokinetics of hydromorphone. Females appear to have higher Cmax (25%) than males with comparable AUC0-24 values. The difference observed in Cmax may not be clinically relevant.