Shownotes
In this episode Ryan and Toxo discuss some potential toxic spices and break down the toxicity and treatment of a once well known medicine
Cinchona Bark, Quinine, and Associated Toxicities
Historical Perspective
Cinchonism
Etiology
- Sources:
- Powdered cinchona bark: Used in tonic water, to treat restless legs, or as a remedy for certain viruses.
- Prescription quinoline derivatives:
- Quinine
- Quinidine
- Hydroxychloroquine
- Chloroquine
Clinical Effects
- Symptoms:
- Dizziness, flushing, headache, tinnitus.
- Potential for vision loss.
- Laboratory Abnormalities:
- Hypoglycemia, hypokalemia, long QRS.
Treatment
Supportive Care:
- Manage airway, breathing, and circulation (ABCs).
- Early use of epinephrine as a preferred pressor based on animal and chloroquine data.
Correct Endocrine/Metabolic Abnormalities:
- Hypertonic Sodium: For wide QRS (use cautiously to avoid worsening hypokalemia).
Decontamination:
- Consider multi-dose activated charcoal for significant ingestions.
Ocular Toxicity
- Key Findings:
- Ocular toxicity is often delayed but can become permanent.
- Quinine levels >15 are associated with increased ocular toxicity.
- Quinine-induced blindness: https://pubmed.ncbi.nlm.nih.gov/3983356/
- Hall AP, et al. Quinine-induced blindness. Br J Ophthalmol. 1997. doi:10.1136/bjo.81.12.1029
- Recovery:
- Vision may recover centrally first, then peripherally.
- Hyperbaric oxygen therapy (HBO) is often used but remains debated.
Ototoxicity
- Mechanism:
- Tinnitus caused by microstructural changes in the outer hair cells of the cochlea and organ of Corti.
- Vasoconstriction and prostaglandin inhibition contribute to decreased hearing.
- Studies:
- Jastreboff PJ, et al. Quinine-induced tinnitus in rats. Arch Otolaryngol Head Neck Surg. 1991. doi:10.1001/archotol.1991.01870220110020
- Roche RJ, et al. Quinine induces reversible high-tone hearing loss. Br J Clin Pharmacol. 1990. doi:10.1111/j.1365-2125.1990.tb03704.x
More on Toxicity from Studies
- Cardiac Arrhythmias in Patients Taking Quinine Alone:Padmaja UK, Adhikari P, Periera P. Experience with quinine in falciparum malaria. Indian J Med Sci. 1999. PMID: 10695226.
- Negative Inotropic Effects of Quinidine:Hoffmeister HM, et al. Negative inotropic effect of class-I antiarrhythmic drugs. Eur Heart J. 1987. doi:10.1093/oxfordjournals.eurheartj.a062178.
- Tinnitus and Hearing Effects: Jarboe JK, Hallworth R. The effect of quinine on outer hair cell shape, compliance and force. Hear Res. 1999. doi:10.1016/s0378-5955(99)00031-3.
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