Vol.:(0123456789) 1 3 Eur Arch Otorhinolaryngol DOI 10.1007/s00405-017-4499-6 LETTER TO THE EDITOR Reply to the letter to the editor concerning: “The therapeutic effect of thymoquinone on acoustic trauma-induced hearing loss in rats” Ozlem Celebi Erdivanli 1  · Mahmut Ogurlu 1  · Engin Dursun 1   Received: 30 January 2017 / Accepted: 31 January 2017 © Springer-Verlag Berlin Heidelberg 2017 study dose (20 mg/kg) with the double dose (40 mg/kg), which is lower than the first quartile considering Al-Ali’s study. The possibility of TQ toxicity was mentioned in the discussion section of our paper, referring to AbuKhader’s paper. However, unpublished data of our pilot experiments with i.p. TQ do not support AbuKhader’s findings. We suc- cessfully administered i.p. doses up to 40 mg/kg, without noticing any side effect such as peritonitis or weight loss. Our study was not powered for studying toxicity, nor is the study designed for that. However, one may note the different drug vehicles in both studies. While AbuKhader prepared the TQ solution by “dissolving in 0.5% dimethyl sulphoxide followed by the addition of olive oil”, we dis- solved TQ in corn oil. It is well known that drug vehicles may affect study results [5]. There is at least one paper describing the additive effect of 1% dimethyl sulphoxide on antifungal activity of TQ [6]. Concerning the results of our encouraging results with corn oil, we chose to not compli- cate our study with biochemical markers, rather depend on meticulous efforts to follow good practice guide for the care and use of animals in research. We have no experience with TQ dissolved in saline, which was used in Aksoy et al.’s study; however, we acknowledge several studies using dis- tilled water or saline to dissolve TQ. We especially appreciate Aksoy et al.’s comments on the total recovery with a 5-day therapy with 10 mg/kg/day of TQ. We would like to emphasize that a shorter duration of treatment may be possible with 20 mg/kg/day of TQ. References 1. Aksoy F, Dogan R, Yenigun A, Veyseller B, Ozturan O, Ozturk B (2015) Thymoquinone treatment for inner-ear acoustic trauma in rats. J Laryngol Otol 129(1):38–45 Dear Editor, Thank you for the opportunity to reply to the letter of Aksoy et al. to our paper “The therapeutic effect of thymo- quinone on acoustic trauma-induced hearing loss in rats”. We would like to thank the authors of the first study reporting the reparative effect of the thymoquinone (TQ) in acoustic trauma induced hearing loss for their comments [1]. We apologize for the misrepresentation about Aksoy et al.’s ABR and DPOAE results at 5th and 10th days of treatment as inferior to the pre-trauma measurements. Ini- tially we wished to highlight the shorter duration of treat- ment with 20 mg/kg of TQ compared to 10 mg/kg. It should be noted that, as emphasized by Aksoy et al.’s reply, the second group in their study received 10 mg/kg of intra- peritoneal (i.p.) TQ for 10 days, making up a total dose of 100 mg/kg. In contrast, our study group received 20 mg/kg of i.p. TQ for 3 days, making up a total dose of 60 mg/kg [2]. This inadvertent mistake occurred during the revision, where the manuscript did undergo significant shortening. The second point, which is about the maximum tolerated dose of TQ reported by AbuKhader [3], is worth a brief discussion. Al-Ali et al. reported LD50 of TQ after i.p., injection in rats as 57.5 mg/kg (45.6–69.4, 95% confidence intervals) [4]. Therefore, in order to adequately power our study with a low number of rats, we chose to compare the This reply refers to the comment available at doi:10.1007/s00405- 017-4495-x. * Ozlem Celebi Erdivanli drozlemcelebi@mynet.com 1 Kulak Burun Boğaz Anabilim Dalı, Recep Tayyip Erdoğan Üniversitesi Eğitim ve Araştırma Hastanesi, İslampaşa mahallesi, 53100 Rize, Turkey