Sparteine

Sparteine at a Glance

Sparteine is a lupine-type (tetracyclic) quinolizidine alkaloid — the principal alkaloid of broom (Cytisus scoparius), a lupin alkaloid, and one of the minor lupine-type alkaloids of blue cohosh (Caulophyllum thalictroides) ^{8,10Reference 8Kennelly EJ et al. · 1999In vitroDetecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo cultureView study →Reference 10Rader JI · 2013Primary constituents of blue cohosh: quantification in dietary supplements and potential for toxicityView study →}. Pharmacologically it has two established faces: a class-I-type cardiac sodium-channel blocker with antiarrhythmic activity, and a historical oxytocic once used to stimulate uterine contractions ^{5,6,7Reference 5Pugsley MK et al. · 1995AnimalThe cardiac electrophysiological effects of sparteine and its analogue BRB-I-28 in the ratView study →Reference 6Honerjäger P et al. · 1986Negative inotropic effects of tetrodotoxin and seven class 1 antiarrhythmic drugs in relation to sodium channel blockadeView study →Reference 7Abtahi FS et al. · 1978AnimalEffect of sparteine sulfate on uterine prostaglandin F in the ratView study →}.

Its lasting importance, though, is neither of those. Sparteine became one of the founding molecules of pharmacogenetics: in 1979 a subset of people were found to metabolise a test dose extremely poorly, and that “sparteine oxidation polymorphism” turned out to be genetic variation in the enzyme now called CYP2D6 ^{1,2Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →}. Sparteine remains a classic CYP2D6 probe substrate, and it also contributes — alongside the related alkaloids lupanine and α-isolupanine — to the cytochrome-P450 inhibition behind blue cohosh’s herb–drug-interaction profile ^{9Reference 9Madgula VL et al. · 2009In vitroAlkaloids and saponins as cytochrome P450 inhibitors from blue cohosh (Caulophyllum thalictroides) in an in vitro assayView study →}.

It carries a moderate toxicity flag: a narrow margin between its cardiac and uterine effects and toxicity is exactly why its therapeutic use was dropped, and the oxytocic action makes it a reproductive concern.

Sparteine & the Birth of Pharmacogenetics

This is the section that makes sparteine matter far beyond its own modest pharmacology. In 1979, Eichelbaum and colleagues reported that when healthy volunteers took sparteine, a distinct minority showed “defective N-oxidation” — they barely metabolised it, accumulated much higher plasma levels, and experienced exaggerated effects ^{1,2Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →}. This split the population into extensive and poor metabolizers, and the trait was inherited ^{1Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →}.

The same year, an independent group found an identical pattern with the antihypertensive debrisoquine. The two defects turned out to be the same deficiency — of a single hepatic enzyme, later cloned and named CYP2D6 ^{3Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}. This “sparteine/debrisoquine oxidation polymorphism” was one of the first demonstrations that ordinary variation in a drug-metabolising gene could explain why the same dose is safe in one person and toxic in another — a founding result of modern pharmacogenetics ^{3Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}.

Roughly 5–10% of people of European ancestry are CYP2D6 poor metabolizers, with the frequency differing markedly between populations ^{3Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}. Because sparteine is oxidised cleanly and specifically by CYP2D6, a single oral test dose with a urinary metabolic ratio became a standard way to phenotype the enzyme — the practical legacy that outlived sparteine’s own use as a drug ^{1,2,3Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}. The enzyme it helped discover now governs the metabolism of a large share of common medicines (many antidepressants, antipsychotics, opioids and beta-blockers), which is why the “sparteine polymorphism” is a fixture of pharmacology teaching. The polymorphism has also been examined as a susceptibility marker — a meta-analysis found only a weak, non-definitive association between CYP2D6 metabolizer status and lung-cancer risk ^{4Reference 4Christensen PM et al. · 1997Meta-analysisThe sparteine/debrisoquine (CYP2D6) oxidation polymorphism and the risk of lung cancer: a meta-analysisView study →}.

What It's Used For

Sparteine’s own pharmacology is real but historical: a cardiac sodium-channel blocker and a uterine stimulant, both once used clinically and both largely abandoned. The strongest, most modern evidence attached to the molecule is not therapeutic at all — it is its role as a metabolic probe (above).

Evidence by IndicationStrength of support · Beta

Support is an experimental score — weighted by study type (human > animal > in vitro) and volume. A beta, not a validated metric. Note that the highest-scoring “application” here is a laboratory probe use, not a treatment; the therapeutic rows are historical.

01CYP2D6 Metabolic Probe (Pharmacogenetics)Promising62%Foundational, replicated human phenotyping data ^{1,2,3Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}

02Antiarrhythmic / Sodium-Channel BlockPromising46%Rodent cardiac electrophysiology + old clinical use ^{5,6Reference 5Pugsley MK et al. · 1995AnimalThe cardiac electrophysiological effects of sparteine and its analogue BRB-I-28 in the ratView study →Reference 6Honerjäger P et al. · 1986Negative inotropic effects of tetrodotoxin and seven class 1 antiarrhythmic drugs in relation to sodium channel blockadeView study →}

03Oxytocic (Uterine Stimulant)Shaky34%Animal uterine-contraction / prostaglandin data + historical obstetric use ^{7Reference 7Abtahi FS et al. · 1978AnimalEffect of sparteine sulfate on uterine prostaglandin F in the ratView study →}

04CYP Inhibition / Herb–Drug InteractionShaky28%In-vitro CYP450 inhibition as a blue cohosh constituent ^{8,9Reference 8Kennelly EJ et al. · 1999In vitroDetecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo cultureView study →Reference 9Madgula VL et al. · 2009In vitroAlkaloids and saponins as cytochrome P450 inhibitors from blue cohosh (Caulophyllum thalictroides) in an in vitro assayView study →}

Mechanisms

The load-bearing point is that sparteine’s two therapeutic mechanisms — the cardiac Na-channel block and the uterine stimulation — both have narrow, hard-to-control margins, while the mechanism that made sparteine famous (being a clean CYP2D6 substrate) is not a therapeutic action at all.

Pharmacokinetics

Sparteine is absorbed after oral dosing and cleared mainly by CYP2D6-mediated oxidation to 2-dehydro- and 5-dehydrosparteine, which are excreted in urine; the ratio of parent to metabolites in urine is the classic phenotyping index ^{1,2Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →}. Its kinetics are the whole reason it is useful — and they are strikingly bimodal. In extensive metabolizers it is oxidised efficiently and cleared quickly; in the 5–10% of Europeans who are poor metabolizers, oxidation is markedly reduced, clearance falls, the half-life is prolonged, and a standard dose produces higher plasma concentrations and exaggerated effects ^{2,3Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}. This genetically determined swing in exposure — rather than any fixed average half-life — is the defining pharmacokinetic fact about the molecule, and the practical hazard behind its old clinical use in an unselected population ^{2Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →}.

Clinical Trials

There is no active therapeutic development of sparteine. Its former uses — as an oxytocic and as a class-I antiarrhythmic (sparteine sulfate) — have been abandoned on safety grounds; its only surviving human role is as a CYP2D6 phenotyping probe ^{1,2,3Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}.

Last checked: July 2026.

Isolate vs. Plant Studies

Sparteine is unusual among plant constituents in that its most important evidence is squarely on the isolated molecule — the pharmacogenetic phenotyping work uses purified sparteine at a defined dose, which is a genuine strength ^{1,2,3Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}. The cardiac and oxytocic pharmacology is likewise isolate-based (rat electrophysiology, isolated-tissue Na-channel studies, rat uterine-prostaglandin work) ^{5,6,7Reference 5Pugsley MK et al. · 1995AnimalThe cardiac electrophysiological effects of sparteine and its analogue BRB-I-28 in the ratView study →Reference 6Honerjäger P et al. · 1986Negative inotropic effects of tetrodotoxin and seven class 1 antiarrhythmic drugs in relation to sodium channel blockadeView study →Reference 7Abtahi FS et al. · 1978AnimalEffect of sparteine sulfate on uterine prostaglandin F in the ratView study →}. Where the evidence turns plant-level is the herb–drug-interaction angle: there, sparteine is one of several lupine-type alkaloids in whole blue cohosh extract, and its contribution to CYP inhibition is inferred from constituent assays rather than shown for the isolate alone ^{8,9Reference 8Kennelly EJ et al. · 1999In vitroDetecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo cultureView study →Reference 9Madgula VL et al. · 2009In vitroAlkaloids and saponins as cytochrome P450 inhibitors from blue cohosh (Caulophyllum thalictroides) in an in vitro assayView study →}. The herbal reputations of broom (cardiac, diuretic, uterine) and blue cohosh (uterine) sit on the whole plant, whose alkaloid content varies so widely by strain, part and season that it cannot be reduced to a sparteine dose ^{10Reference 10Rader JI · 2013Primary constituents of blue cohosh: quantification in dietary supplements and potential for toxicityView study →}.

Prevalence in Nature

Sparteine is a lupine-type quinolizidine alkaloid of the legume tribe Genisteae. It is the principal alkaloid of broom (Cytisus scoparius, synonym Sarothamnus scoparius), a constituent of lupins (Lupinus spp.), and one of the minor lupine-type alkaloids identified in blue cohosh rhizome (Caulophyllum thalictroides), alongside lupanine, α-isolupanine and 5,6-dehydro-α-isolupanine ^{8Reference 8Kennelly EJ et al. · 1999In vitroDetecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo cultureView study →}. Like other quinolizidine alkaloids it is biosynthesised from the amino acid lysine (via cadaverine and the quinolizidine pathway) as a chemical-defence compound ^{12Reference 12Namdar D et al. · 2024New Analytical Approach to Quinolizidine Alkaloids and Their Assumed Biosynthesis Pathways in Lupin SeedsView study →}.

Reliable quantitative figures for sparteine specifically are scarce: its content in broom and lupins varies widely with species, strain, plant part, season and provenance, and blue cohosh analyses have quantified the marker alkaloids (N-methylcytisine, baptifoline, anagyrine) far more consistently than sparteine ^{8,10Reference 8Kennelly EJ et al. · 1999In vitroDetecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo cultureView study →Reference 10Rader JI · 2013Primary constituents of blue cohosh: quantification in dietary supplements and potential for toxicityView study →}. No trustworthy per-source concentration for the isolate has been established.

Discovery & Synthesis

Sparteine was first isolated from broom in the 19th century, and its name comes from Spartium — the old genus name for the broom that also gives us the tribe Genisteae; the alkaloid is likewise known as lupinidine for its occurrence in lupins. It is one of the classic, long-studied lupin/quinolizidine alkaloids, and its complex tetracyclic bis-quinolizidine skeleton made it a recurring target and tool in alkaloid chemistry. Beyond medicine, (−)-sparteine is widely used as a chiral diamine ligand in asymmetric synthesis (notably in enantioselective organolithium chemistry) — a role in the laboratory quite separate from its biology. First-isolation attribution and the earliest total synthesis are not documented in detail here.

Patents: not yet researched.

Toxicity & Safety

Sparteine carries a moderate flag. It is less acutely poisonous than the nicotinic quinolizidine cytisine, but it is a bioactive cardiac and uterine agent with a narrow margin — the very reason its clinical use as an antiarrhythmic and oxytocic was dropped. Its cardiac Na-channel block can slow conduction and provoke arrhythmia at excessive exposure, and that risk is amplified in CYP2D6 poor metabolizers, in whom a normal dose behaves like an overdose ^{2,5,6Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 5Pugsley MK et al. · 1995AnimalThe cardiac electrophysiological effects of sparteine and its analogue BRB-I-28 in the ratView study →Reference 6Honerjäger P et al. · 1986Negative inotropic effects of tetrodotoxin and seven class 1 antiarrhythmic drugs in relation to sodium channel blockadeView study →}.

Its oxytocic action makes it a reproductive-safety concern: sparteine stimulates uterine contraction and raises uterine prostaglandin F ^{7Reference 7Abtahi FS et al. · 1978AnimalEffect of sparteine sulfate on uterine prostaglandin F in the ratView study →}, and historical obstetric use was abandoned partly because contractions could become excessive and uncontrolled. Note that within blue cohosh the most serious documented hazards — nicotinic toxicity and teratogenicity — belong to the sibling alkaloids N-methylcytisine and anagyrine, not to sparteine itself ^{8,11Reference 8Kennelly EJ et al. · 1999In vitroDetecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo cultureView study →Reference 11Green BT et al. · 2010Actions of piperidine alkaloid teratogens at fetal nicotinic acetylcholine receptorsView study →}; but sparteine is part of the alkaloid burden of these plants and of the CYP-inhibition that underlies their herb–drug-interaction potential ^{9Reference 9Madgula VL et al. · 2009In vitroAlkaloids and saponins as cytochrome P450 inhibitors from blue cohosh (Caulophyllum thalictroides) in an in vitro assayView study →}. As a plant exposure, broom, blue cohosh and under-processed lupins should not be ingested casually.

Reproductive note (prose only): sparteine’s uterotonic/oxytocic activity is a documented isolate finding ^{7Reference 7Abtahi FS et al. · 1978AnimalEffect of sparteine sulfate on uterine prostaglandin F in the ratView study →} and is the reason it is treated as a substance to avoid around pregnancy. Per house policy, the pregnancy/lactation verdict for any product belongs to the relevant herb or supplement page, where intake is decided, not to this molecule page. No comprehensive isolate reproductive-toxicity dataset is characterised here beyond the oxytocic pharmacology above.

Safety at a Glance

⚠️ Moderate toxicity

• Useful as a research probe. As an isolated, defined-dose CYP2D6 substrate, sparteine has a clean, well-characterised laboratory use ^{1,2,3Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}.
• Narrow cardiac margin. A class-I-type Na-channel blocker whose conduction effects can themselves be arrhythmogenic at excessive exposure — the reason its antiarrhythmic use was abandoned ^{5,6Reference 5Pugsley MK et al. · 1995AnimalThe cardiac electrophysiological effects of sparteine and its analogue BRB-I-28 in the ratView study →Reference 6Honerjäger P et al. · 1986Negative inotropic effects of tetrodotoxin and seven class 1 antiarrhythmic drugs in relation to sodium channel blockadeView study →}.
• Oxytocic — a reproductive concern. Stimulates uterine contraction and raises uterine prostaglandin F in animals; historical obstetric use was dropped for lack of control ^{7Reference 7Abtahi FS et al. · 1978AnimalEffect of sparteine sulfate on uterine prostaglandin F in the ratView study →}.
• Exaggerated effects in CYP2D6 poor metabolizers. ~5–10% of Europeans clear it slowly, so a standard exposure can act like an overdose ^{2,3Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}.
• Part of the blue cohosh / broom / lupin alkaloid load. Contributes to CYP inhibition and to the general caution against ingesting these plants; the teratogenic alkaloids of blue cohosh are others ^{8,9,11Reference 8Kennelly EJ et al. · 1999In vitroDetecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo cultureView study →Reference 9Madgula VL et al. · 2009In vitroAlkaloids and saponins as cytochrome P450 inhibitors from blue cohosh (Caulophyllum thalictroides) in an in vitro assayView study →Reference 11Green BT et al. · 2010Actions of piperidine alkaloid teratogens at fetal nicotinic acetylcholine receptorsView study →}.

Dosage

There is no current recommended human dose for sparteine. Sparteine sulfate was formerly administered as an oxytocic and as a class-I antiarrhythmic, but that therapeutic use has been abandoned on safety grounds ^{5,6,7Reference 5Pugsley MK et al. · 1995AnimalThe cardiac electrophysiological effects of sparteine and its analogue BRB-I-28 in the ratView study →Reference 6Honerjäger P et al. · 1986Negative inotropic effects of tetrodotoxin and seven class 1 antiarrhythmic drugs in relation to sodium channel blockadeView study →Reference 7Abtahi FS et al. · 1978AnimalEffect of sparteine sulfate on uterine prostaglandin F in the ratView study →}. The only surviving human application is as a low single oral test dose used to phenotype CYP2D6 — measured by the urinary metabolic ratio, this is a diagnostic/research procedure, not a treatment, and has itself been largely superseded by direct genotyping ^{1,2,3Reference 1Eichelbaum M et al. · 1979Defective N-oxidation of sparteine in man: a new pharmacogenetic defectView study →Reference 2Eichelbaum M et al. · 1979Influence of the defective metabolism of sparteine on its pharmacokineticsView study →Reference 3Zanger UM · 2013Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variationView study →}.

Herbal exposure is indirect — via broom, blue cohosh, or insufficiently debittered lupins — at alkaloid concentrations that are not reliably quantified and that vary widely by species, strain, plant part and season ^{8,10Reference 8Kennelly EJ et al. · 1999In vitroDetecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo cultureView study →Reference 10Rader JI · 2013Primary constituents of blue cohosh: quantification in dietary supplements and potential for toxicityView study →}. These are historical clinical and research figures, not a personal recommendation.

References

1. Eichelbaum M, et al. (1979). Defective N-oxidation of sparteine in man: a new pharmacogenetic defect. European Journal of Clinical Pharmacology. https://pubmed.ncbi.nlm.nih.gov/499318/
2. Eichelbaum M, et al. (1979). Influence of the defective metabolism of sparteine on its pharmacokinetics. European Journal of Clinical Pharmacology. https://pubmed.ncbi.nlm.nih.gov/499319/
3. Zanger UM, Schwab M (2013). Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variation. Pharmacology & Therapeutics. https://pubmed.ncbi.nlm.nih.gov/23333322/
4. Christensen PM, et al. (1997). The sparteine/debrisoquine (CYP2D6) oxidation polymorphism and the risk of lung cancer: a meta-analysis. European Journal of Clinical Pharmacology. https://pubmed.ncbi.nlm.nih.gov/9049580/
5. Pugsley MK, et al. (1995). The cardiac electrophysiological effects of sparteine and its analogue BRB-I-28 in the rat. European Journal of Pharmacology. https://pubmed.ncbi.nlm.nih.gov/8788447/
6. Honerjäger P, et al. (1986). Negative inotropic effects of tetrodotoxin and seven class 1 antiarrhythmic drugs in relation to sodium channel blockade. Naunyn-Schmiedeberg’s Archives of Pharmacology. https://pubmed.ncbi.nlm.nih.gov/2422563/
7. Abtahi FS, et al. (1978). Effect of sparteine sulfate on uterine prostaglandin F in the rat. Prostaglandins. https://pubmed.ncbi.nlm.nih.gov/725080/
8. Kennelly EJ, et al. (1999). Detecting potential teratogenic alkaloids from blue cohosh rhizomes using an in vitro rat embryo culture. Journal of Natural Products. https://pubmed.ncbi.nlm.nih.gov/10543898/
9. Madgula VL, et al. (2009). Alkaloids and saponins as cytochrome P450 inhibitors from blue cohosh (Caulophyllum thalictroides) in an in vitro assay. Planta Medica. https://pubmed.ncbi.nlm.nih.gov/19137500/
10. Rader JI, Pawar RS (2013). Primary constituents of blue cohosh: quantification in dietary supplements and potential for toxicity. Analytical and Bioanalytical Chemistry. https://pubmed.ncbi.nlm.nih.gov/23420136/
11. Green BT, et al. (2010). Actions of piperidine alkaloid teratogens at fetal nicotinic acetylcholine receptors. Neurotoxicology and Teratology. https://pubmed.ncbi.nlm.nih.gov/20116429/
12. Namdar D, et al. (2024). New Analytical Approach to Quinolizidine Alkaloids and Their Assumed Biosynthesis Pathways in Lupin Seeds. Toxins. https://pubmed.ncbi.nlm.nih.gov/38535829/

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