Barking Up the Wrong Tree (Cinohonism, Quinine & Quinidine)

In this episode Ryan and Toxo discuss some potential toxic spices and break down the toxicity and treatment of a once well known medicine

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

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

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:

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.

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

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.