is no ceiling effect to analgesia, such as is seen with partial agonists or non-opioid analgesics.
Based upon a single-dose, relative-potency study conducted in humans with cancer pain, 10 to
15 mg of oxycodone given intramuscularly produced an analgesic effect similar to 10 mg of
morphine given intramuscularly. Both drugs have a 3 to 4 hour duration of action. Oxycodone
retains approximately one half of its analgesic activity when administered orally.
Effects on Central Nervous System: The precise mechanism of the analgesic action is
unknown. However, specific CNS opioid receptors for endogenous compounds with opioidlike activity have been identified throughout the brain and spinal cord and play a role in the
analgesic effects of this drug. A significant feature of opioid-induced analgesia is that it
occurs without loss of consciousness. The relief of pain by morphine-like opioids is relatively
selective, in that other sensory modalities, (e.g., touch, vibrations, vision, hearing, etc.) are not
obtunded.
Oxycodone produces respiratory depression by direct action on brain stem respiratory centers.
The respiratory depression involves both a reduction in the responsiveness of the brain stem
respiratory centers to increases in carbon dioxide tension and to electrical stimulation.
Oxycodone depresses the cough reflex by direct effect on the cough center in the medulla.
Antitussive effects may occur with doses lower than those usually required for analgesia.
Oxycodone causes miosis, even in total darkness. Pinpoint pupils are a sign of opioid
overdose but are not pathognomonic (e.g., pontine lesions of hemorrhagic or ischemic origins
may produce similar findings). Marked mydriasis rather than miosis may be seen due to
hypoxia in overdose situations.
Effects on Gastrointestinal Tract And Other Smooth Muscle: Oxycodone, like other opioid
analgesics, produces some degree of nausea and vomiting which is caused by direct
stimulation of the chemoreceptor trigger zone (CTZ) located in the medulla. The frequency
and severity of emesis gradually diminishes with time.
Oxycodone may cause a decrease in the secretion of hydrochloric acid in the stomach that
reduces motility while increasing the tone of the antrum, stomach, and duodenum. Digestion
of food in the small intestine is delayed and propulsive contractions are decreased. Propulsive
peristaltic waves in the colon are decreased, while tone may be increased to the point of
spasm resulting in constipation. Other opioid-induced effects may include a reduction in
biliary and pancreatic secretions, spasm of sphincter of Oddi, and transient elevations in
serum amylase.
Effects on Cardiovascular System: Oxycodone, in therapeutic doses, produces peripheral
vasodilatation (arteriolar and venous), decreased peripheral resistance, and inhibits
baroreceptor reflexes. Manifestations of histamine release and/or peripheral vasodilatation
may include pruritus, flushing, red eyes, sweating, and/or orthostatic hypotension.
Caution should be used in hypovolemic patients, such as those suffering acute myocardial
infarction, because oxycodone may cause or further aggravate their hypotension. Caution
should also be used in patients with cor pulmonale who have received therapeutic doses of
opioids. Head Injury and Increased Intracranial Pressure:
The respiratory depressant effects of narcotics and their capacity to elevate cerebrospinal fluid
pressure may be markedly exaggerated in the presence of head injury, other intracranial
lesions or a pre-existing increase in intracranial pressure. Furthermore, narcotics produce
adverse reactions which may obscure the clinical course of patients with head injuries.
PRECAUTIONS
General:
ROXICODONE® tablets are intended for use in patients who require oral pain therapy with
an opioid agonist. As with any opioid analgesic, it is critical to adjust the dosing regimen
individually for each patient (see DOSAGE AND ADMINISTRATION).
Selection of patients for treatment with ROXICODONE® should be governed by the same
principles that apply to the use of other potent opioid analgesics. Opioid analgesics given on a
fixed-dosage schedule have a narrow therapeutic index in certain patient populations,
especially when combined with other drugs, and should be reserved for cases where the
benefits of opioid analgesia outweigh the known risks of respiratory depression, altered
mental state, and postural hypotension. Physicians should individualize treatment in every
case, using nonopioid analgesics, prn opioids and /or combination products, and chronic
opioid therapy with drugs such as ROXICODONE® (oxycodone hydrochloride) in a
progressive plan of pain management such as outlined by the World Health Organization, the
Agency for Health Care Policy and Research, and the American Pain Society.
Use of ROXICODONE® is associated with increased potential risks and should be used only
with caution in the following conditions: acute alcoholism; adrenocortical insufficiency (e.g.,
Addison’s disease); convulsive disorders; CNS depression or coma; delirium tremens;
debilitated patients; kyphoscoliosis associated with respiratory depression; myxedema or
hypothyroidism; prostatic hypertrophy or urethral stricture; severe impairment of hepatic,
pulmonary or renal function; and toxic psychosis.
The administration of ROXICODONE®, like all opioid analgesics, may obscure the diagnosis
or clinical course in patients with acute abdominal conditions. Oxycodone may aggravate
convulsions in patients with convulsive disorders, and all opioids may induce or aggravate
seizures in some clinical settings.