Generic Name

Oxycontin

Brand Names

for a sustained‑release formulation of oxycodone, a potent μ‑opioid receptor agonist. It is indicated for the management of moderate to severe pain that requires continuous, around‑the‑clock opioid therapy.

Mechanism

• Selective activation of μ‑opioid receptors on dorsal horn neurons → ↓ nociceptive signal transmission.
• Disruption of *ascending* pain pathways and enhancement of *descending* inhibitory pathways.
• Resultant analgesia is maintained over 12 hours via a polymer matrix that controls drug release.

Pharmacokinetics

• Absorption
• Oral bioavailability ≈ 60 % (slightly higher than immediate‑release oxycodone).
• Peak plasma concentrations (C_max) reached ~4–6 h after dosing.
• Distribution
• Large volume of distribution (~1.2–1.3 L/kg).
• Crosses the blood‑brain barrier efficiently, leading to central analgesic effects.
• Metabolism
• Hepatic CYP2D6 → *N‑desmethyl‑oxycodone* (active).
• CYP3A4 → *O‑demethyl‑oxycodone* (inactive).
• Genetic polymorphisms in CYP2D6 significantly affect analgesic response and risk of side effects.
• Elimination
• Renal excretion of metabolites (~70 % of dose).
• Elimination half‑life ≈ 3–4 h for oxycodone; sustained release prolongs analgesia over 12 h.

Indications

• Chronic, neuropathic, or post‑surgical pain requiring continuous opioid coverage.
• Situations where immediate‑release formulations result in uncontrolled breakthrough pain.

Contraindications

• Contraindications
• Known hypersensitivity to oxycodone or any formulation component.
• Severe respiratory insufficiency or chronic obstructive pulmonary disease at advanced stages.
• Acute or severe bronchial asthma.
• Warnings
• High abuse potential; risk of dependence, tolerance, and withdrawal.
• Respiratory depression, especially when combined with CNS depressants (benzodiazepines, alcohol).
• Pitfall: near‑total endogenous opioid deficiency in opioid‑naïve patients may precipitate withdrawal.

Dosing

• Initial dose (opioid‑naïve): *10 mg once daily* (12 h release).
• Titrate: Increase by 10 mg increments every 3–5 days based on pain control and tolerability.
• Maximum: 60 mg/day (though ≤ 30 mg/day is common in most patients).
• Switching: If transitioning from immediate‑release oxycodone, hold the immediate formulation overnight and start Oxycontin the next day at an equivalent total daily dose.
• Administration: Swallow whole; crushing or chewing is strongly discouraged (increases release rate, potential overdose).
• Maintenance: Continue as long as analgesia persists; taper slowly when indicated.

Adverse Effects

• Common (≥ 10 %)
• Nausea, vomiting, constipation.
• Dizziness, somnolence, dry mouth.
• Headache, muscle cramps.
• Serious
• Respiratory depression (most dangerous; monitor in high‑risk patients).
• Hypotension, bradycardia (in overdose).
• Seizures (rare, precipitated by abrupt discontinuation or alcohol use).
• Hallucinations, psychosis (in susceptible individuals).
• Missed Dose → withdrawal symptoms: agitation, muscle aches, lacrimation, piloerection, insomnia.

Monitoring

• Pain scores (Numeric Rating Scale) every 48–72 h during titration.
• Opioid‑tolerance markers: escalating doses to maintain analgesia.
• Respiratory rate and O₂ saturation in patients ≥ 65 y, chronic lung disease, or opioid‑naïve.
• Liver function tests: baseline, then every 3–6 mo in patients with hepatic impairment.
• Urine drug screening in high‑risk or suspected abusers.
• Patient‑reported constipation; implement bowel regimen.

Clinical Pearls

• Use a “Take‑home” dose‑taper schedule: for patients needing dose reduction, give the last full dose the day before withdrawal.
• Adrenaline rescue: CHRONIC‑OPIOID NON–RESPONDERS often benefit from co‑prescribing glucocorticoids or NSAIDs (dual‑mode analgesia).
• Gastric decontamination: In an overdose, activated charcoal is ineffective after >1 h, but naloxone remains first‑line treatment.
• Withdrawal prevention: Combine oxycodone with a non‑opioid adjunct (e.g., gabapentin) to blunt withdrawal severity.
• Pregnancy and lactation: Oxycontin is category C; estimated plasma transfer into breast milk is low (~0.4 %). If prescribed, weigh pain control vs. neonatal opioid exposure.

> Key Takeaway: Oxycontin’s extended‑releasing design delivers reliable 12‑hour analgesia but requires careful dose titration, abuse‑prevention measures, and vigilant monitoring to mitigate respiratory depression and constipation.

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• *(Prepared for medical students and healthcare professionals; references available upon request.)*