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

• Use of Cinchona Bark Powder for Malaria:
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4973170/
• Evolutionary Pressure of Malaria on Sickle Cell Traits:
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3499995/

Cinchonism

• Definition: Classic toxicities caused by ingestion of quinoline derivatives from cinchona bark.
• Brief Review:
• https://pubmed.ncbi.nlm.nih.gov/32644745/

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

1. 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.
2. 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.
3. 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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