Severe hypotension may occur in patients whose ability to maintain blood pressure already has been compromised by hypovolemia or concurrent use of drugs such as phenothiazines or general anesthetics. Drug may cause orthostatic hypotension in ambulatory patients. Use caution in patients with circulatory shock. Physical dependence assumes clinically significant proportions only after several weeks of continued use. Rate of development of tolerance varies from patient to patient.
Detoxification is unlikely for the cancer patient.
If syndrome becomes severe, patient may be given methadone. Administration shortly before delivery may result in neonatal respiratory depression, especially if high doses are used. Safety and effectiveness not established. Ureteral spasm, spasm of vesical sphincters, urinary retention. Sedation, drowsiness, mental clouding, lethargy, impairment of mental and physical performance, anxiety, fear, dysphoria, dizziness, psychic dependence, mood changes.