Oxycodone

Drug Reference 9 min 1699

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Created On: 27/09/2019

Oxycodone is a phenantherne derivative with opioid analgesic activity similar to morphine but adverse effects are milder than those of morphine. Oxycodone is used to control moderate to severe pain, including postoperative, post extractional, and postpartum pain and other opiates such as morphine and codeine act as agonists at opiate receptors within the central nervous system (CNS).

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Introduction

Pharmacological Class: Opioid analgesic

Indications

Moderate to Severe Pain

Pharmachologic action

Oxycodone is a pure opioid agonist whose principal therapeutic action is analgesia. The mechanism of action of oxycodone involves: binding to mu-type opioid receptors, inhibition of adenylyl-cyclase and hyperpolarisation of neurons, and decreased excitability. However, binding to the opiate receptors in CNS causes an inhibition of ascending pain pathways, alteration of the perception and response to pain and produces generalized CNS depression.

Dosage

Initial dose in opioid-naive patients: 5 to 15 mg orally every 4 to 6 hours
Initial dose for opioid-naive and opioid non-tolerant patients: 10 mg orally every 12 hours

Pharmacokinetics

Oxycodone is well absorbed with an absolute bioavailability of 60%-87%. Volume of distribution is found to be 2.6 L/kg and plasma protein binding is 45%. A high fat meal can increase the absorption by 25%. Extensively metabolized to weaker and inactive metabolites and plasma half-life is 4.5 hours. Eliminated primarily in the urine as the parent compound and its metabolites

Contraindications

In patients with known hypersensitivity to oxycodone or aspirin
In situations where opioids are contraindicated including patients with significant respiratory depression (in unmonitored settings or the absence of resuscitative equipment) and patients with acute or severe bronchial asthma or hypercarbia.
In the setting of suspected or known paralytic ileus.

Drug interaction

Oxycodone is metabolized in part to oxymorphone via the cytochrome p450 isoenzyme CYP2D6. While this pathway may be blocked by a variety of drugs (e.g., certain cardiovascular drugs and antidepressants), such blockade has not yet been shown to be of clinical significance with this agent.
Oxycodone enhances the neuromuscular blocking action of skeletal muscle relaxants and produces an increased respiratory depression.
Mixed Agonist/Antagonist Opioid Analgesics (i.e., pentazocine, nalbuphine, butorphanol and buprenorphine) should be administered with caution to patients who have received or are receiving a course of therapy with a pure opioid agonist analgesic such as oxycodone hydrochloride tablets.
Monoamine Oxidase Inhibitors (MAOIs) have been reported to intensify the effects of at least one opioid drug causing anxiety, confusion and significant depression of respiration or coma.

Side effects

Common (affecting between 1 in 10 to 1 in 100)

Nausea and vomiting
Loss of appetite
Dry mouth
Stomach pain
Flushing
Sweating
Weakness
Headache
Mood changes

Uncommon (affecting 1 in 100 to 1 in 1000)

Spasm of a Bile Duct Tract
Widening of Blood Vessels
Head Pain
Incomplete or Infrequent Bowel Movements
Seizures
Constipation

Very rare (affecting less than 1 in 10,000)

Chest pain
Irregular heartbeat
Hives
Rash
Itching
Swelling of face, tongue, throat, lips, eyes, feet, hands, ankles, or lower legs
Difficulty breathing or swallowing
Extreme drowsiness
Lightheadedness when changing positions

Precautions

Should be given with caution or in reduced doses to patients with hypothyroidism, adrenocortical insufficiency, asthma or decreased respiratory reserve, renal or hepatic impairment, prostatic hyperplasia, hypotension, shock, inflammatory or obstructive bowel disorders, or myasthenia gravis. Dosage should be reduced in elderly or debilitated patients.
Should be given with care to infants, especially neonates. Their use during labour may cause respiratory depression in the neonate.
Discontinuation of therapy with Oxycodone should be carried out gradually in patients who may have developed physical dependence, to avoid precipitating withdrawal symptoms.
As it causes drowsiness, driving or machinery should not be operated.

Clinical evidence

Oxycodone is a strong opioid that acts at mu and kappa opioid receptors. It has a specific pharmacologic profile and greater analgesic potency to morphine. Oxycodone offers a fast onset of analgesia, controlling pain for 12 hours and providing clinically meaningful relief of moderate to severe pain and improving quality of life across a broad spectrum of pain types. It has relevant points of difference from other opioids and as such may be a suitable alternative to morphine.¹
Analgesics for children with acute abdominal pain are often withheld for fear that they might mask physical examination findings and thus might be unsafe. Although early administration of buccal oxycodone provides a significant pain relief to children with acute abdominal pain, without adversely altering the clinical signs or obscuring the surgical diagnosis.²