Datura

Tachycardia is a near-universal feature of anticholinergic toxidrome. Patients with pre-existing cardiovascular disease face elevated risk of hemodynamically significant arrhythmia. A fatal cardiac arrhythmia was documented in a Datura poisoning case (Le Garff 2016).

Pre-existing tachyarrhythmias are exacerbated by anticholinergic vagal blockade. Fatal cardiac arrhythmia has been documented in Datura poisoning (Le Garff 2016). This is both a substance-specific and class-level contraindication.

Anticholinergic agents may exacerbate myasthenia gravis by disrupting the cholinergic signaling that compensatory mechanisms depend upon. This is a class-level anticholinergic contraindication applying to all muscarinic antagonists.

Datura exposure may precipitate acute psychosis in individuals with or without prior psychiatric history. In a 29-year review by the Swiss Toxicology Information Center, 12 of 17 severe D. stramonium intoxications presented with psychosis. Individuals with a history of psychotic disorders face elevated risk of prolonged or treatment-resistant psychotic episodes.

Scopolamine undergoes significant CYP3A4-mediated first-pass metabolism (oral bioavailability 3–27%). Hepatic impairment may reduce first-pass clearance, increasing systemic alkaloid exposure. No direct Datura-specific data exist for this interaction — assessment is based on pharmacokinetic mechanism.

Muscarinic M3 blockade relaxes the detrusor muscle while sphincter tone is maintained, precipitating acute urinary retention. Patients with pre-existing urinary obstruction or benign prostatic hyperplasia are at highest risk. Urinary retention is a hallmark of anticholinergic toxidrome documented across Datura case series.

Scopolamine readily crosses the placental barrier, as documented in pharmacokinetic studies. Fetal exposure to anticholinergic agents carries risk of developmental effects. No controlled safety data exist for Datura exposure during pregnancy.

Elderly individuals have heightened sensitivity to anticholinergic toxicity, with greater risk of cognitive impairment, falls, delirium, and cardiovascular complications at lower doses than younger adults. Age-related decline in cholinergic reserve amplifies the effects of muscarinic blockade.

Pediatric patients develop severe anticholinergic syndrome from smaller quantities of plant material than adults. An 8-year-old with accidental D. stramonium ingestion presented with aggression, agitation, delirium, and visual hallucinations (PMID 25341608). Lower body mass and immature hepatic metabolism increase susceptibility.

Anticholinergic-induced mydriasis can trigger acute angle-closure glaucoma — a medical emergency requiring immediate treatment to prevent permanent vision loss. All Datura preparations cause mydriasis via muscarinic M3 blockade in the iris sphincter.

Concurrent use of any medication with anticholinergic properties — tricyclic antidepressants, first-generation antihistamines, antipsychotics, antiparkinsonian agents, bladder antimuscarinics, antiemetics — produces additive or synergistic anticholinergic toxicity. Pharmacovigilance data show the average anticholinergic drug burden in adverse events reaches 2.4 concurrent atropinic drugs. Severity: potentially life-threatening.

Anticholinergic agents are absolutely contraindicated in paralytic ileus. M3 muscarinic blockade reduces gastrointestinal motility; in a patient with existing ileus, this may precipitate bowel necrosis or perforation. This is a class-level anticholinergic contraindication.