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

Target Organ Systems

• respiratory
• renal

Interactions

• Alprazolam (major): Additive respiratory depression. Black-box warning. [Jones 2015]
• Mirtazapine (caution): Additive CNS depression. [Jones 2015]

Pathways It Modulates

• Opioid receptor signaling (activator) — MOR full agonist

Chemical Identifiers

• PubChem CID: 5288826
• Formula: C17H19NO3
• Molecular weight: 285.34 g/mol
• InChIKey: BQJCRHHNABKAKU-KBQPJGBKSA-N
• SMILES: CN1CC[C@]23[C@@H]4[C@H]1CC5=C2C(=C(C=C5)O)O[C@H]3[C@H](C=C4)O

References

• PMID 11510626
• PMID 26143953
• PMID 9686407