Oral isotretinoin may improve patient hearing at all audiometric frequencies, according to new research published in the September issue of the International Journal of Dermatology.
For the study, the researchers wanted to investigate whether oral isotretinoin could affect patients’ hearing, as measured by audiometry and tympanometry. "The adverse effects of isotretinoin are well known, but ototoxic effects have rarely been reported," wrote Dr. Hayriye Karabulut, of Ankara Kecioren Research and Training Hospital in Turkey, and his colleagues.
The researchers enrolled 47 patients with moderate to severe nodulocystic acne (Int. J. Dermatol. 2011;50:1139-43). Of the 38 patients (76 ears) who completed the study, 15 were male, and 23 were female. Female subjects of childbearing potential used two methods of birth control and had a negative pregnancy test 1 week before initiating therapy. Patients ranged in age from 15 to 34 years (mean, 20 years).
The researchers prescribed oral isotretinoin 0.5-0.75 mg/kg body weight twice daily for at least 3 months. They evaluated biochemical parameters at baseline and at 1-month follow-up, and conducted a physical examination, including otoscopy.
They also conducted audiometric tests at baseline and weeks 1, 2, and 3. These included pure-tone, speech, and high-frequency audiometry, as well as ipsi- and contralateral acoustic reflexes. They measured air conduction pure-tone averages (PTAs) at frequencies of 250 Hz (PTA1); 500, 1,000, 2,000 Hz (PTA2); 4,000, 8,000 and 10,000 Hz (PTA3); and 12,500, 16,000, 18,000 and 20,000 Hz (PTA4) for each ear.
The otoscopic exam was normal in all patients before and after initiation of treatment, the researchers reported. There were no changes in speech discrimination scores. Oral isotretinoin, which is a derivative of retinol (vitamin A), improved the hearing level of the patients in all audiometric frequencies in the short-period follow-up study.
Compared with baseline scores, the hearing thresholds of patients were increased in middle frequency (PTA2 and PTA3) during the first week of follow-up, in low frequency (PTA1) during the second week of follow-up, and in high and ultrahigh frequency (PTA4) during the third week of follow-up. Specific results included the following:
• PTA1 went from a mean 10.1 decibels (dB) at baseline to 9.5 dB at week 1, and to 9.0 dB at weeks 2 and 3.
• PTA2 went from a mean 7.1 dB at baseline to 6.3 dB at week 1, to 6.1 dB at week 2, and to 5.8 dB at week 3.
• PTA3 went from 10.1 dB at baseline to 7.7 dB at week 1, to 8.0 dB at week 2, and to 6.8 dB at week 3.
• PTA4 went from 44.4 dB at baseline to 42.2 dB at week 1, to 40.7 dB at week 2, and to 38.9 dB at week 3.
"Because oxidative stress has been suggested to be involved in hearing impairment, antioxidants are expected to play a preventive role," the researchers noted. "It is also known that retinoic acid, an active metabolite of retinol, is indispensable for normal development of the Corti organ. The association between vitamin A (retinol) and the prevention of hearing impairment in particular has been focused on because the concentration of vitamin A in the inner ear has been shown to be high."
Oral isotretinoin is used to treat extensive and nodulocystic acne, as well as moderate acne that does not respond to conventional treatment. Teratogenicity and a high risk of spontaneous abortion are known risks of treatment with the drug.
The authors did not disclose having any conflicts of interest.