Beware! Don’t let ototoxic drugs ruin your hearing!

Many people still remember the "Thousand-Handed Guanyin" program at the 2005 Spring Festival Gala. While these dancers brought us an audio-visual feast, they also brought deaf patients into the public eye and received widespread attention. However, 18 of the 21 performers were deafened by drugs, which shocked "my friends and I!" How could drugs used to treat diseases suddenly become "poisons"? Today, the pharmacist will take you to know these ototoxic drugs and teach you how to prevent drug-induced deafness.

First, let us understand drug-induced deafness, which refers to hearing loss caused by toxic damage to the auditory nervous system caused by the use of certain drugs for treatment or human contact with certain chemical agents, accompanied by vertigo, tinnitus, dizziness, nausea, unsteady walking or complete deafness. [1] Most of these clinical manifestations occur 1-2 weeks after medication, and gradually worsen, becoming stable after half a year. Deafness is often bilaterally symmetrical, starting with high-frequency hearing loss and gradually extending to low frequencies. Accompanying symptoms may appear before or after deafness. The degree of hearing loss caused by this varies greatly, and severe cases may lead to complete deafness. [2] In addition, drugs can also cause damage to the liver, kidney, hematopoietic, endocrine, and nervous systems.

So far, more than 100 drugs in 18 categories have been proven to affect hearing. The mechanism of deafness-causing drugs in each category is different.

Some deafness is reversible, while others cause permanent hearing loss.[3] Below, the pharmacist will focus on several common ototoxic drugs:

1. Antibiotics

1. Aminoglycosides: including streptomycin, neomycin, gentamicin, tobramycin, amikacin, and metronidazole.

Among all patients with drug-induced deafness, aminoglycoside antibiotics are the most common cause, but the pathogenesis of its ototoxicity is still under study. This type of drug mainly affects the auditory and vestibular systems of the inner ear. In the early stages, it can also damage the vestibule or cochlea. In the late stages, usually both parts are damaged, causing severe sensorineural deafness.

2. Macrolides: mainly erythromycin, azithromycin, etc. This type of drug can cause bilateral hearing loss or tinnitus. The severity is often related to the dose. It usually occurs 4-8 days after taking the drug and can be recovered after stopping the drug.

3. Tetracyclines: such as tetracycline, oxytetracycline, doxycycline, minocycline, etc. Studies have shown that the dose-dependency of tetracycline-induced ototoxicity is very obvious, that is, the greater the dose used, the greater the possibility of ototoxicity; at the same time, when it is used in combination with diuretics, the ototoxicity is significantly increased.

4. Fluoroquinolones: including norfloxacin, levofloxacin, ciprofloxacin, moxifloxacin, etc. This type of drug is widely used in clinical practice. Ototoxicity has been reported for oral or intravenous administration, and symptoms are usually relieved or disappear after drug discontinuation.

5. Others: There are reports of ototoxic symptoms in clinical use of antibiotics such as ampicillin, cefazolin, cefradine, vancomycin, polymyxin B, isoniazid, and metronidazole.

2. Antipyretic and analgesic drugs: such as aspirin, indomethacin, etc. These drugs mainly produce ototoxicity to the base of the cochlea, which often manifests as high-frequency hearing loss in the early stage and can cause symptoms such as tinnitus, dizziness, and imbalance, which usually disappear within 24-48 hours after stopping the drug.

3. Diuretics: such as edenic acid, furosemide, bumetanide, etc. The ototoxicity of this type of drugs is mostly related to the dose. Long-term, large-dose, rapid intravenous administration can lead to bilateral symmetrical deafness accompanied by tinnitus. The deafness can be restored by stopping the drug in a short period of time, but it is easy to cause permanent deafness when used in combination with renal insufficiency or aminoglycosides.

4. Anti-tumor drugs: such as cisplatin, carboplatin, vincristine, nitrogen mustard, etc. These drugs can cause hearing impairment and irreversible high-frequency hearing loss, which is related to the dosage and duration of medication.

5. Antimalarial drugs: such as quinine and chloroquine, whose ototoxicity is mainly tinnitus and deafness. Short-term discontinuation of the drug can restore hearing, but long-term high-dose use often causes irreversible hearing damage.

6. Others: In addition to the above-mentioned ototoxic drugs, local anesthetics (lucaine, lidocaine, tetracaine, etc.), heavy metals (lead, mercury, cadmium, etc.), etc. can also cause deafness and tinnitus. In severe cases, it can cause permanent damage to other nervous systems including hearing.

Once a person is sick, he or she will inevitably have to take medicine and get injections. You can’t just stop taking medicine and not treat the disease. In fact, drug-induced deafness is related to the toxicity of the drug itself, the dosage of the drug, the length of the treatment course, the age of the person taking the drug, individual differences, susceptibility and genetics. Ototoxic drugs mainly damage the inner ear and cause the inner ear cells to atrophy and degenerate. If tinnitus occurs after taking some drugs, such as aspirin, stopping the drug in time can restore the damage to the inner ear. However, some drugs, such as streptomycin, can cause irreversible permanent deafness. [3]

When ototoxic drugs damage hearing, some drugs such as vitamin A, vitamin B, coenzyme A, etc. have certain therapeutic effects in the early stages of drug-induced deafness, but deafness is basically irreversible, so the key is prevention!

Pharmacists recommend that you pay attention to the following points when using drugs that may cause deafness:

1. Strictly follow the indications and medication time of these drugs, take the medicine according to the doctor's orders, do not increase the dosage by yourself, and do not use it for a long time.

2. Aminoglycosides should be prohibited for patients with a family history of poisoning and nephritis.

3. Ototoxic drugs should be prohibited for infants, the elderly, pregnant women, and patients with sensorineural hearing loss.

4. Avoid the combined use of diuretics, chemotherapy drugs and aminoglycosides.

5. While taking ototoxic drugs, people should have their hearing checked regularly if possible, and stop taking the drugs immediately if their condition permits.

During medication, closely observe for early symptoms of poisoning, such as ear swelling, tinnitus, deafness, dizziness, numbness of the face and tongue, and unsteady walking. If any symptoms are found, the medication should be stopped immediately and medical attention should be sought promptly.

【References】

[1] Li Xianlong. Beware of drug-induced deafness[J]. Yunnan Science and Technology Management, 2018, 31(01):45.

[2] Yao Shi. These ototoxic drugs should be used with caution[J]. Jiangsu Health Care, 2018(09):31

[3] Liu Shijing. Drug-induced deafness and its prevention and treatment strategies[J]. Chinese Community Physician, 2010, 26(16):12.

[4] Jiang Desheng. Don’t let drugs ruin your hearing[J]. Chinese Medicine Health and Wellness, 2016(09):66