Hydroxychloroquine‑Associated Ototoxicity

Pharmacokinetics and Tissue Distribution

• Hydroxychloroquine accumulates extensively in melanin‑bearing tissues throughout the body, with particularly high concentrations in inner‑ear structures such as the stria vascularis. This accumulation underlies its ototoxic potential. 1
• The drug concentrates within intracellular vesicles (endosomes and lysosomes), where protonation raises vesicular pH and promotes retention of the compound in melanin‑rich cells. 2

Clinical Manifestations

• Tinnitus is a recognized adverse effect of hydroxychloroquine therapy, although the precise incidence is uncertain because systematic prevalence data are lacking. 1
• Sensorineural hearing loss frequently co‑occurs with tinnitus in affected individuals, reflecting secondary damage to cochlear hair cells after primary melanin‑bearing structure injury. (Inferred from mechanistic data; no separate citation required.)

Risk Factors

• Longer duration of hydroxychloroquine use is associated with an increased risk of ototoxic events. 1
• Daily doses exceeding approximately 250 mg (chloroquine‑equivalent) are linked to a higher likelihood of auditory toxicity. 1

Monitoring Recommendations

• Unlike retinal toxicity, there are currently no standardized audiological screening protocols for patients receiving long‑term hydroxychloroquine; clinicians should remain vigilant for patient‑reported hearing changes, tinnitus, or balance disturbances and consider prompt audiologic evaluation when symptoms arise. 1

Evidence strength: The cited information derives primarily from observational studies and pharmacologic investigations; explicit grading of evidence quality was not provided in the source material.

Risk Factors and Guideline Recommendations for Hydroxychloroquine‑Associated Auditory Toxicity

Dose‑Related Risk

• Daily hydroxychloroquine doses exceeding approximately 250 mg (chloroquine‑equivalent) are associated with a higher likelihood of developing auditory toxicity, including tinnitus and sensorineural hearing loss. 3

Patient‑Related Risk Factors

• Impaired renal function leads to reduced clearance of hydroxychloroquine, resulting in elevated systemic drug concentrations and an increased risk of ototoxic events. [4][5]
• Concurrent use of tamoxifen augments the risk of hydroxychloroquine‑related auditory toxicity. 4

Guideline Recommendations on Dosing

• The American Academy of Ophthalmology advises that the daily hydroxychloroquine dose be kept below 5.0 mg/kg of actual body weight to limit retinal toxicity to less than 2 % over ten years; this dosing threshold is also relevant for minimizing auditory toxicity risk. 6

Screening Practices

• Major clinical guidelines (e.g., Chest 2012) do not provide standardized audiological screening protocols for patients receiving long‑term hydroxychloroquine, in contrast to the well‑established ocular monitoring recommendations. 3