: Morphine chemical structure (morphinan opioid), 2D skeletal formula, C17H19NO3

Morphine Chemical Structure

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1. Identification

Summary

Morphine is a natural phenanthrene (morphinan) opioid indicated for moderate–severe pain when alternative treatments are inadequate. Analgesia, respiratory/CNS depression, miosis, constipation, histamine-mediated pruritus, tolerance, dependence, and withdrawal are characteristic class effects.

Brand Names

MS Contin, Kadian, Oramorph, Statex; numerous generics (region-dependent)

Name

Morphine

Background

Primary alkaloid of Papaver somniferum (opium poppy); supplied mainly as sulfate or hydrochloride salts in immediate- and extended-release oral, parenteral, epidural, and intrathecal formulations.

Modality

Small molecule

Groups

Approved; prescription/controlled substance (jurisdiction-specific scheduling)

Structure

Morphine 2D chemical structure (phenanthrene/morphinan core with 4,5-epoxy bridge). Formula C17H19NO3; IUPAC (5α,6α)-7,8-didehydro-4,5-epoxy-17-methylmorphinan-3,6-diol; CAS 57-27-2.
Morphine chemical structure (morphinan opioid), 2D skeletal formula, C17H19NO3

Weight

~285.34 g/mol (free base)

Chemical Formula

C₁₇H₁₉NO₃

Synonyms

3,6-dihydroxy-N-methylmorphinan; (5α,6α)-7,8-didehydro-4,5-epoxy-17-methylmorphinan-3,6-diol; (−)-morphine

External IDs

CAS (base): 57-27-2; PubChem CID: 5288826; UNII: 76I7G6D29C; ATC: N02AA01; KEGG: D08233; ChEBI: 17303

2. Pharmacology

Indication

Management of moderate to severe acute or chronic pain where opioid analgesia is appropriate and alternatives are insufficient.

Associated Conditions

Cancer pain, palliative care, postoperative pain, vaso-occlusive crises (sickle cell), trauma; neuraxial use for obstetric/operative analgesia.

Associated Therapies

Monotherapy or combined in multimodal regimens (acetaminophen/NSAIDs, adjuvants). Neuraxial single-dose or infusion per protocol.

Contraindications & Blackbox Warnings

Boxed warnings (class): addiction, abuse, misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal; risks with benzodiazepines/CNS depressants. Contraindications include significant respiratory depression, acute/severe bronchial asthma without monitoring, GI obstruction, and known hypersensitivity.

Pharmacodynamics

μ-opioid receptor agonist → inhibition of ascending nociceptive transmission and modulation in brain/spinal cord; κ/δ agonism contributes. Histamine release may cause vasodilation/pruritus.

Mechanism of action

G-protein–coupled μ-receptor activation ↓ cAMP, opens K⁺ channels, inhibits Ca²⁺ influx → reduced neurotransmitter release and neuronal excitability.

Absorption

Oral bioavailability ~20–40% (high first-pass metabolism); t_max ~0.5–1 h (IR; formulation-dependent). Food effect minimal for many products; follow label.

Volume of distribution

~1–6 L/kg (widely distributed; limited BBB penetration vs more lipophilic opioids).

Protein binding

~20–35% (albumin/α₁-acid glycoprotein).

Metabolism

Predominantly UGT2B7 glucuronidation to morphine-3-glucuronide (M3G, major, inactive/aversive) and morphine-6-glucuronide (M6G, active analgesic); minor N-demethylation.

Route of elimination

Primarily renal as glucuronides; ~5–10% unchanged; minor biliary excretion/enterohepatic cycling.

Half-life

~2–4 h (IV ~2 h; prolonged in hepatic/renal impairment).

Clearance

~20–30 mL/min/kg (population-dependent). Accumulation of M6G in renal impairment.

Adverse Effects

Sedation, dizziness, nausea/vomiting, constipation, pruritus, urinary retention; serious: respiratory depression, hypotension, adrenal insufficiency, androgen deficiency, anaphylactoid reactions.

Toxicity

Overdose: miosis, coma, respiratory depression; treat with airway support and naloxone (repeat/infuse as needed due to metabolite kinetics).

Pathways

μ-receptor signaling; UGT2B7 conjugation; renal elimination of conjugates.

Pharmacogenomic Effects/ADRs

No required PGx. Variability in UGT2B7, ABCB1 (P-gp), and renal function influences exposure/response; caution with renal impairment (M6G accumulation).

3. Interactions

Drug Interactions

CNS depressants (benzodiazepines, alcohol, sedatives): additive respiratory/CNS depression.
Mixed agonist–antagonists/partial agonists (buprenorphine, nalbuphine, pentazocine): reduced effect/precipitated withdrawal.
MAOIs: avoid within recommended washouts (serotonergic/CNS risks).
P-gp and enzyme modulators: can alter CNS penetration and exposure (clinical relevance product- and patient-specific).

Food Interactions

Product-specific; many ER products unaffected by food; follow individual labeling.

4. Categories

ATC Codes

N02AA01 (natural opium alkaloids — morphine)

Drug Categories

Opioid analgesic; μ-receptor agonist; Small molecule; Natural product

Chemical Taxonomy

Morphinan/phenanthrene alkaloid; 4,5-epoxy bridge, 3,6-diol; chiral, rigid polycyclic scaffold

Affected organisms

Humans (therapeutic use)

5. Chemical Identifiers

UNII

76I7G6D29C

CAS number

57-27-2

InChI Key

BQJCRHHNABKAKU-KBQPJGBKSA-N

InChI

InChI=1S/C17H19NO3/c1-18-7-6-17-10-3-5-13(20)16(17)21-15-12(19)4-2-9(14(15)17)8-11(10)18/h2-5,10-11,13,16,19-20H,6-8H2,1H3/t10-,11+,13-,16-,17-/m0/s1

IUPAC Name

(5α,6α)-7,8-didehydro-4,5-epoxy-17-methylmorphinan-3,6-diol

SMILES

CN1CC[C@@]23C4=CC(O)=C5O[C@H]2C@@HC=CC[C@H]3[C@H]1C45

6. References

PubChem Compound Summary — Morphine (CID 5288826); formula C17H19NO3, mass ~285.34 g/mol; identifiers (SMILES/InChI/Key). PubChem
NIST Chemistry WebBook — Standard InChI and InChIKey BQJCRHHNABKAKU-UHFFFAOYSA-N; CAS 57-27-2. NIST WebBook+1
FDA GSRS/UNII — UNII 76I7G6D29C record for morphine. precisionFDA
ATC/DDD Index — N02AA01 (morphine) classification. FHI+1
IUPHAR/BPS Guide to Pharmacology — ligand entry, μ-agonist class context and identifiers. guidetopharmacology.org
StatPearls (2025 update) — bioavailability ~<40%, Vd 1–6 L/kg, protein binding 20–35%, clearance ~20–30 mL/min/kg, t½ ~2 h IV, renal excretion of glucuronides with ~10% unchanged. NCBI
KEGG DRUG — morphine/morphine sulfate entries, ATC code and pathway notes. KEGG+1

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