Morphine

Category: alkaloid

Aliases: MS Contin, Avinza, Oramorph

Pharmacological Mechanism

Prototype µ-opioid agonist. Also binds κ and δ opioid receptors with lower affinity. Analgesia is µ-mediated; respiratory depression, euphoria, miosis, and GI hypomotility are µ effects. Metabolised primarily by UGT2B7 → morphine-6-glucuronide (active, potent analgesic) and morphine-3-glucuronide (not analgesic, neuroexcitatory — accumulates in renal failure).

Half-Life (t½)

PO: 2.5h, IV: 2.5h, IM: 2.5h, SC: 2.5h, IN: 2.5h

Dosing Guidelines

• PO: Typical 6.67mg (Range: 5 - 10 mg)
• IV: Typical 6.67mg (Range: 5 - 10 mg)
• IM: Typical 6.67mg (Range: 5 - 10 mg)
• SC: Typical 6.67mg (Range: 5 - 10 mg)
• IN: Typical 6.67mg (Range: 5 - 10 mg)
• TD: Typical 6.67mg (Range: 5 - 10 mg)

Target Organ Systems

• respiratory
• renal

Interactions

• Alprazolam
• Mirtazapine