Oxymorphone Hydrochloride Tablets are an opioid agonist indicated for the relief of moderate to severe acute pain where the use of an opioid is appropriate. ()
Yes and no. They are both used to treat pain, and share the same molecular backbone (they have similar structures), along with two other important opiates, morphine and thebaine. But there are a number of differences. Oxycodone has only been around for about a century, and is a man-made semisynthetic drug, whilst codeine is a natural substance, from the opium poppy, Papaver somniferum (photo, right). Codeine and morphine are the two natural painkillers made by the opium poppy.
: Long-term studies have been completed to evaluate the carcinogenic potential of oxymorphone in both Sprague-Dawley rats and CD-1 mice. Oxymorphone was administered to Sprague-Dawley rats (2.5, 5, and 10 mg/kg/day in males and 5, 10, and 25 mg/kg/day in females) for 2 years by oral gavage. The systemic drug exposure (AUC ng•h/mL) at the 10 mg/kg/day dose in male rats was 0.34-fold and at the 25 mg/kg/day dose in female rats was 1.5-fold the human exposure at a dose of 260 mg/day. No evidence of carcinogenic potential was observed in rats. Oxymorphone was administered to CD-1 mice (10, 25, 75 and 150 mg/kg/day) for 2 years by oral gavage. The systemic drug exposure (AUC ng•h/mL) at the 150 mg/kg/day dose in mice was 14.5-fold (in males) and 17.3-fold (in females) times the human exposure at a dose of 260 mg/day. No evidence of carcinogenic potential was observed in mice.
Increases in the activity of the CYP 2C9 and CYP 3A4 isoforms occurred when oxymorphone was incubated with human hepatocytes. However, clinical drug interaction studies with oxymorphone hydrochloride ER showed no induction of CYP450 3A4 or 2C9 enzyme activity, indicating that no dose adjustment for CYP 3A4- or 2C9-mediated drug-drug interactions is required.
: Oxymorphone hydrochloride was not mutagenic when tested in the bacterial reverse mutation assay (Ames test) at concentrations of ≤5270 μg/plate, or in an mammalian cell chromosome aberration assay performed with human peripheral blood lymphocytes at concentrations ≤5000 μg/ml with or without metabolic activation. Oxymorphone hydrochloride tested positive in both the rat and mouse micronucleus assays. An increase in micronucleated polychromatic erythrocytes occurred in mice given doses of ≥250 mg/kg and in rats given doses of 20 and 40 mg/kg. A subsequent study demonstrated that oxymorphone hydrochloride was not aneugenic in mice following administration of up to 500 mg/kg. Additional studies indicate that the increased incidence of micronucleated polychromatic erythrocytes in rats may be secondary to increased body temperature following oxymorphone administration. Doses associated with increased micronucleated polychromatic erythrocytes also produce a marked, rapid increase in body temperature. Pretreatment of animals with sodium salicylate minimized the increase in body temperature and prevented the increase in micronucleated polychromatic erythrocytes after administration of 40 mg/kg oxymorphone.
Oxymorphone Hydrochloride Tablets are a semi-synthetic opioid analgesic supplied in 5 mg and 10 mg tablet strengths for oral administration. The tablet strengths describe the amount of oxymorphone hydrochloride per tablet. The tablets contain the following inactive ingredients: magnesium stearate, microcrystalline cellulose, and pregelatinized starch.
The opioid antagonist naloxone hydrochloride is a specific antidote against respiratory depression that may result from overdosage or unusual sensitivity to opioids including oxymorphone hydrochloride. Nalmefene is an alternative pure opioid antagonist, which may be administered as a specific antidote to respiratory depression resulting from opioid overdose. Since the duration of action of oxymorphone hydrochloride may exceed that of the antagonist, keep the patient under continued surveillance and administer repeated doses of the antagonist according to the antagonist labeling as needed to maintain adequate respiration.
In the treatment of oxymorphone hydrochloride overdosage, primary attention should be given to the re-establishment of a patent airway and institution of assisted or controlled ventilation. Supportive measures (including oxygen and vasopressors) should be employed in the management of circulatory shock and pulmonary edema accompanying overdose as indicated. Cardiac arrest or arrhythmias may require cardiac massage or defibrillation.
In patients receiving oxymorphone hydrochloride, opioid antagonists should not be administered in the absence of clinically significant respiratory or circulatory depression. Administer opioid antagonists cautiously to persons who are known, or suspected to be, physically dependent on any opioid agonist including oxymorphone hydrochloride. In such cases, an abrupt or complete reversal of opioid effects may precipitate an acute abstinence syndrome. In an individual physically dependent on opioids, administration of the usual dose of the antagonist will precipitate an acute withdrawal syndrome. The severity of the withdrawal syndrome produced will depend on the degree of physical dependence and the dose of the antagonist administered. If respiratory depression is associated with muscular rigidity, administration of a neuromuscular blocking agent may be necessary to facilitate assisted or controlled ventilation. Muscular rigidity may also respond to opioid antagonist therapy.
Oxymorphone hydrochloride may cause 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 origin may produce similar findings). Marked mydriasis rather than miosis may be seen with hypoxia in overdose situations .
Acute overdosage with oxymorphone hydrochloride is characterized by respiratory depression (a decrease in respiratory rate and/or tidal volume, Cheyne- Stokes respiration, cyanosis), extreme somnolence progressing to stupor or coma, skeletal muscle flaccidity, cold and clammy skin, constricted pupils, and sometimes bradycardia and hypotension. In some cases, apnea, circulatory collapse, cardiac arrest, and death may occur.
Chemically, oxymorphone hydrochloride is 4, 5α-epoxy-3, 14-dihydroxy-17-methylmorphinan-6-one hydrochloride, a white or slightly off-white, odorless powder, which is sparingly soluble in alcohol and ether, but freely soluble in water. The molecular weight of oxymorphone hydrochloride is 337.80. The pK1 and pK2 of oxymorphone at 37°C are 8.17 and 9.54, respectively. The octanol/aqueous partition coefficient at 37°C and pH 7.4 is 0.98.