The most serious adverse experience encountered during administration of Astramorph/PF is respiratory depression and/or respiratory arrest. This depression and/or respiratory arrest may be severe and could require intervention. (See WARNINGS and OVERDOSAGE) Because of delay in maximum CNS effect with intravenously administered drug (30 min), rapid administration may result in overdosing. Single-dose neuraxial administration may result in acute or delayed respiratory depression for periods at least as long as 24 hours.
Tolerance and Myoclonus:
See WARNINGS for discussion of these and related hazards.
While low doses of intravenously administered morphine have little effect on cardiovascular stability, high doses are excitatory, resulting from sympathetic hyperactivity and increase in circulating catecholamines. Excitation of the central nervous system, resulting in convulsions, may accompany high doses of morphine given intravenously. Dysphoric reactions may occur after any size dose and toxic psychoses have been reported.
Single-dose epidural or intrathecal administration is accompanied by a high incidence of pruritus that is dose-related but not confined to the site of administration. Pruritus, following continuous infusion of epidural or intrathecal morphine, is occasionally reported in the literature; these reactions are poorly understood as to their cause.
Urinary retention, which may persist 10 to 20 hours following single epidural or intrathecal administration, is a frequent side effect and must be anticipated primarily in male patients, with a somewhat lower incidence in females. Also frequently reported in the literature is the occurrence of urinary retention during the first several days of hospitalization for the initiation of continuous intrathecal or epidural morphine therapy. Patients who develop urinary retention have responded to cholinomimetic treatment and/or judicious use of catheters (see PRECAUTIONS).
Constipation is frequently encountered during continuous infusion of morphine; this can usually be managed by conventional therapy.
Lumbar puncture-type headache is encountered in a significant minority of cases for several days following intrathecal catheter implantation; this, generally, responds to bed rest and/or other conventional therapy.
Other adverse experiences reported following morphine therapy include-- Dizziness, euphoria, anxiety, depression of cough reflex, interference with thermal regulation and oliguria. Evidence of histamine release such as urticaria, wheals and/or local tissue irritation may occur. Nausea and vomiting are frequently seen in patients following morphine administration.
Pruritus, nausea/vomiting and urinary retention, if associated with continuous infusion therapy, may respond to intravenous administration of a low dose of naloxone (0.2 mg). The risks of using narcotic antagonists in patients chronically receiving narcotic therapy should be considered.
In general, side effects are amenable to reversal by narcotic antagonists.
NALOXONE INJECTION AND RESUSCITATIVE EQUIPMENT SHOULD BE IMMEDIATELY AVAILABLE FOR ADMINISTRATION IN CASE OF LIFE-THREATENING OR INTOLERABLE SIDE EFFECTS AND WHENEVER ASTRAMORPH/PF THERAPY IS BEING INITIATED.