Dose-response relationship of topically applied mitomycin C for the prevention of laser myringotomy closure.
OBJECTIVE
We sought to determine a dose-response curve for topical mitomycin C when used to prolong the patency of laser-assisted myringotomies.


METHODS
Bilateral myringotomies were performed using the argon laser in 40 guinea pigs with normal ears. Pledgets with (0.05, 0.2, 0.4, or 2.0 mg/mL) mitomycin C were applied topically. Monitoring consisted of weekly or biweekly otomicroscopy.


RESULTS
As in previous studies, all saline-treated myringotomies closed by day 7. By day 14, all myringotomies (100%) in the 0.05 mg/mL group were closed. By contrast, all myringotomies (100%) remained patent in the 0.2 and 0.4 mg/mL treatment groups, and 56% of the myringotomies remained patent in the 2.0 mg/mL group at day 14. By day 56, all myringotomies were closed in the 2.0 mg/mL group, 5 (50%) myringotomies were patent in the 0.4 mg/mL group, and 1 (11%) myringotomy was patent in the 0.2 mg/mL group. The study was terminated on day 84 (12 weeks). At that time, only the 0.4 mg/mL group had patent myringotomies (n = 3; 30%). The highest dose (2.0 mg/mL) of mitomycin was significantly associated with otorrhea. Otorrhea also appeared to be associated with earlier myringotomy closure.


CONCLUSIONS
There is a dose-response curve for topical mitomycin C when used for prolonging myringotomy patency in doses up to 0.4 mg/mL. Higher doses do not appear to prolong patency and are associated with greater otorrhea, suggesting middle ear toxicity.
Department of Otolaryngology, University of Miami School of Medicine, Miami, FL, USA.
David
D
Jassir
Onur
O
Odabasi
Orlando
O
Gomez-Marin
Craig A
CA
Buchman
D000287:Administration, Topical; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D053685:Laser Therapy / Q000379:methods*; D008876:Middle Ear Ventilation / Q000379:methods; D016685:Mitomycin / Q000008:administration & dosage / Q000627:therapeutic use*; D009225:Myringoplasty / Q000379:methods*; D019384:Nucleic Acid Synthesis Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D011183:Postoperative Complications / Q000517:prevention & control*; D011897:Random Allocation; D014432:Tympanic Membrane / Q000187:drug effects* / Q000601:surgery*; D014945:Wound Healing / Q000187:drug effects
D019384:Nucleic Acid Synthesis Inhibitors; D016685:Mitomycin