Noscapine — Narcotine (Phthalideisoquinoline · Non-opioid Antitussive · Tubulin-binding Anticancer)

Compound	Noscapine (Narcotine / l-Noscapine)
Chemical class	Alkaloid — Isoquinoline / Phthalideisoquinoline (Non-opioid antitussive)
CAS	128-62-1
Primary source	Papaver somniferum (opium, approximately 6% of latex — highest of the major opium alkaloids after morphine)
Key applications	Non-addictive antitussive; tubulin-binding anticancer lead; sigma receptor agonist; informational reference
Claim strength	High (antitussive); Moderate (anticancer preclinical); Informational only (supplement)
Typical form	Pharmaceutical antitussive tablet; available OTC in some markets; research anticancer agent
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Name origin: Noscapine (formerly narcotine or l-noscapine) was isolated from opium in 1817 by Pierre-Jean Robiquet (who also isolated codeine). The name “narcotine” reflected its original (incorrect) assumption of narcotic activity. Noscapine is a phthalideisoquinoline alkaloid — structurally distinct from morphine and papaverine, with no opioid receptor activity. It constitutes approximately 6% of opium dry weight — significantly more than thebaine or papaverine — making it the third most abundant major opium alkaloid after morphine (~12%) and codeine (~4%). Pharmacology — sigma receptor and tubulin: Noscapine’s antitussive mechanism involves sigma receptor agonism, modulating cough reflex via brainstem sigma receptors. Unlike codeine, it has no opioid receptor activity and no addiction potential. Separately, noscapine is a tubulin-binding agent (interacts with the colchicine binding site) with anticancer properties discovered in the 1990s — noscapine arrests cancer cells in mitosis by disrupting the mitotic spindle without general cytotoxicity to normal cells. Clinical status: Noscapine is approved as an OTC antitussive in many countries (UK, Ireland, Scandinavia, Australia, India) but is not approved in the US (where it is available only as a research compound). Multiple anticancer clinical trials of noscapine analogues are underway. Supplement status: Pharmaceutical antitussive in some markets; research anticancer agent. Not a dietary supplement.

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Evidence for Noscapine Applications

Antitussive — non-addictive (clinical): Multiple clinical comparisons confirm noscapine’s antitussive efficacy comparable to codeine in productive and non-productive cough, without the addiction potential, respiratory depression risk, or CYP2D6 pharmacogenetic issues of codeine. It is the antitussive of choice in many markets for patients where opioid-class antitussives are inappropriate (elderly, CYP2D6 poor metabolisers, patients on interacting drugs). Claim strength: High (clinical evidence).

Anticancer — tubulin-binding (preclinical and early clinical): Noscapine binds β-tubulin at the colchicine binding site (different from taxol binding site) and arrests cancer cells in mitosis without causing severe bone marrow suppression at preclinical efficacious doses. Noscapine and its synthetic analogue EM011 (Br-noscapine) have shown efficacy in multiple cancer cell lines and animal tumour models. Phase I/II clinical trials have been conducted in multiple myeloma and glioblastoma. The anticancer profile — effective at oral doses, minimal toxicity — makes noscapine an unusually well-positioned natural product anticancer candidate. Claim strength: Moderate (early clinical trials; not approved).

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Frequently Asked Questions — Noscapine

Why is noscapine not available in the US as an antitussive?
Noscapine has never been submitted for FDA approval as an antitussive in the US — there was no commercial driver to pursue approval for a non-patent-protected compound when dextromethorphan and codeine were already established. Its availability in other markets reflects historical regulatory decisions rather than pharmacological inferiority. The FDA’s 2023 conclusion that oral phenylephrine is ineffective as a decongestant has raised questions about other OTC respiratory ingredients, but noscapine is not currently in the US regulatory pipeline.

Can noscapine be used in children?
Yes — noscapine’s non-opioid mechanism makes it appropriate for paediatric antitussive use in markets where it is approved, unlike codeine (banned for children) and dextromethorphan (not recommended under 6 years in most guidelines). In UK and some other markets, noscapine is approved for children from 2 years. The antitussive evidence in paediatric populations is more limited than in adults but the safety profile (no respiratory depression, no addiction) is clearly superior to codeine.

Is noscapine being developed as a cancer drug?
Yes — multiple research groups and biotech companies have pursued noscapine as an anticancer agent. Synthetic analogues with improved potency (Br-noscapine, EM011) are in preclinical and early clinical development. Phase I trials have established safety in humans at doses relevant to anticancer activity. The unusual properties — oral bioavailability, minimal bone marrow toxicity, tubulin-binding mechanism distinct from existing microtubule drugs — make noscapine an attractive anticancer lead. Commercial development is hampered by the non-patent-protected status of noscapine itself (only novel analogues can be patented).

Does noscapine interact with warfarin?
Yes — noscapine is a documented CYP2C9 inhibitor. CYP2C9 is the primary metabolic enzyme for warfarin (S-warfarin). Noscapine co-administration increases warfarin plasma levels, potentially causing supratherapeutic anticoagulation and bleeding risk. This interaction is the most clinically significant noscapine drug interaction and should be flagged in any formulation or clinical context where both agents might be used. INR monitoring is essential if noscapine is co-administered with warfarin.

Related compounds: Codeine, Morphine, Papaverine, Narceine

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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