Cytisus scoparius · PhytoNexus

01 Identity and provenance

Accepted binomial: Cytisus scoparius
Common names: Scotch Broom
Family (APG IV): Fabaceae
Part used: Herb
Verification tier: Tier 2 · Verified Clinical columns reviewed and a source is on record.
Reviewer note (2026 audit): Drugs.com NPP Broom monograph | Eichelbaum M et al. (sparteine/CYP2D6 polymorphism) | Meyler’s Side Effects of Drugs, sparteine | VERIFIED 2026 (batch 4) - synthetic analogue, application, interactions, side effects and references populated from retrieved primary/regulatory sources. Interactions labelled CLINICAL vs THEORETICAL. Marketed-formulation column intentionally blank. | HOST FACTOR

02 Constituent chemistry

Chemical class	Marker compound	Synthetic analogue in use
Quinolizidine alkaloids	Sparteine Herb	Class 1a antiarrhythmics (FUNCTIONAL - sparteine is a sodium-channel blocker). Oxytocin (functional, for the oxytocic action). Both uses abandoned.

The analogue column is what makes the interaction reasoning tractable: where a constituent has a marketed structural counterpart, the counterpart's interaction profile is the starting hypothesis for the plant.

Looking up structures and physicochemical properties from PubChem…

03 Stated application

Reported activity: Historical antiarrhythmic and oxytocic; BOTH ABANDONED for narrow therapeutic index and safer alternatives. Sparteine survives as the classic PROBE SUBSTRATE for CYP2D6 phenotyping. Clinical trials do not support any current pharmacological use of the herb.
Reported adverse effects: PHARMACOGENOMIC HAZARD - THE POINT OF THIS ENTRY. Sparteine oxidation is CYP2D6-dependent and 5-10% of Caucasians are poor metabolisers who eliminate it slowly and are at higher risk of adverse effects. The consequence is stark: at recommended antiarrhythmic doses, essentially only poor metabolisers reach therapeutic concentrations, while about 90% of the population stays subtherapeutic - the same dose is simultaneously too much and too little depending on genotype. Toxicity: dizziness, drowsiness, headache, sweating, mydriasis, myasthenia; curare-like neuromuscular block leading to respiratory arrest. 30 mg/kg was fatal to a young child. CONTRAINDICATED IN PREGNANCY - powerful oxytocic; tetanic uterine contraction, abruptio placentae and uterine rupture reported. Also contraindicated in cardiomyopathy and hypertension.

04 Interaction matrix

Source column, verbatim: CLINICAL: CYP2D6 inhibitors (quinidine, haloperidol, moclobemide) slow sparteine metabolism - monitor. CYP2D6 handles roughly a quarter of clinical drugs, so this entry is a marker for a much wider interaction space.
Normalised onto 1 canonical drug class below.

Curated from the reviewed source

Drug class	Severity	Mechanism type	Provenance	Expected effect
Monoamine oxidase inhibitors CNS	4Contraindicated	PD-additive	curated A	Hypertensive crisis, hyperpyrexia, serotonin syndrome, intracranial haemo…	why ▾
Class mechanism. Beta-carboline (harmine, harmaline) and related botanical alkaloids are themselves reversible MAO-A inhibitors. Combined with a prescribed MAOI, or with tyramine-rich food or sympathomimetics, the pressor and serotonergic reserve is abolished. Expected Hypertensive crisis, hyperpyrexia, serotonin syndrome, intracranial haemorrhage. Management Absolute contraindication. Apply the full MAOI dietary and drug restriction list to the botanical as well. Onset rapid Evidence A - human data with a cited source Matched on “moclobemide” Find evidence for this pair Map this mechanism

Predicted from constituent chemistry

These edges are not clinical findings. Each one is a rule inference: a constituent class in this plant is known to act on a target that the drug class also acts on. They are shown because a blank cell reads as “safe”, and for a Tier 1 entry a blank cell only means “not yet looked at”. Treat them as a literature-search agenda, not as a warning.

Drug class	Severity	Mechanism type	Provenance	Expected effect
Narrow-therapeutic-index CYP3A4 substrates Pharmacokinetic	4Contraindicated	PK-CYP3A4	predicted D	Toxic accumulation or subtherapeutic failure of the co-prescribed drug, s…	why ▾
Chemistry of this pair. Alkaloidal bases have pH-dependent absorption and commonly interact with hepatic CYP isoenzymes and efflux transporters. Class mechanism. Furanocoumarins, bergamottin, piperine, glabridin and berberine inhibit CYP3A4; hyperforin, andrographolide and several diterpenes induce it through PXR. Because CYP3A4 handles roughly half of marketed drugs, the affected list is broad and the direction is product-specific. Expected Toxic accumulation or subtherapeutic failure of the co-prescribed drug, sometimes fatal for antiarrhythmics, immunosuppressants and oncology agents. Management Screen the full regimen for 3A4 substrates. Where the substrate has a narrow index, avoid rather than monitor. Onset unspecified Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism
Antacids, PPIs and H2 blockers Gastrointestinal	2Moderate	PK-absorption	predicted D	Reduced or erratic absorption of alkaloids; heartburn and reflux from pre…	why ▾
Chemistry of this pair. Alkaloidal bases have pH-dependent absorption and commonly interact with hepatic CYP isoenzymes and efflux transporters. Class mechanism. Gastric pH elevation alters the dissolution and ionisation of alkaloidal and enteric-coated botanical products; menthol- and peppermint-oil products lose their enteric protection at high pH and can be released prematurely. Expected Reduced or erratic absorption of alkaloids; heartburn and reflux from premature release of volatile-oil preparations. Management Separate administration by 2 hours. Avoid non-enteric peppermint oil in reflux disease. Onset unspecified Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism

05 Hazard register

pharmacogenomic - CYP2D6 poor metabolisers (5-10%) at risk while

06 Confusable material

These entries could be mistaken for this one in trade, in the herbarium, or in a prescription. Powdered material is often indistinguishable, so the check is macroscopic, microscopic and chromatographic rather than nominal.

Ruscus aculeatus

Butcher's Broom

Asparagaceae

Shares the common name "broom"

07 Mechanism map

Chemistry sorts to the left, pharmacology to the right. Dashed edges are predicted. Drag nodes, scroll to zoom, export at 3× for a figure.

species

chemical class

marker compound

drug class

expected effect

hazard

08 Open literature

Abstract-scoped query built from this binomial, its common names and its marker compounds, run live against Europe PMC, PubMed and OpenAlex, then ranked locally against an evidence hierarchy.

Checking openFDA spontaneous reports…

09 Isomechanistic neighbours

Species whose interaction profile overlaps this one, ranked by shared severity weight rather than by count — a shared contraindication counts for more than a shared minor signal. Practical use: these are the plants you should not stack with this one, because the mechanisms summate.

Species	Family	Shared classes	Jaccard
Rauvolfia serpentina Sarpagandha	Apocynaceae	3	0.50
Catharanthus roseus Periwinkle	Apocynaceae	3	0.50
Ephedra sinica Ephedra	Ephedraceae	3	0.38
Mucuna pruriens Mucuna	Fabaceae	3	0.60
Alstonia scholaris Saptaparna	Apocynaceae	3	0.50
Physostigma venenosum Calabar Bean	Fabaceae	3	0.38

10 References and notes

Source column: EFSA Panel. EFSA J 2019;17:5860 (quinolizidine alkaloids)

EFSA Panel. EFSA J 2019

2019 manual

17:5860 (quinolizidine alkaloids)

manual

BibTeX for all 2 records

@article{anon2019,
  title = {EFSA Panel. EFSA J 2019},
  year = {2019},
}

@article{anon,
  title = {17:5860 (quinolizidine alkaloids)},
}

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