The pH of Commonly used Topical Ear Drops in the Treatment of Otitis Externa

Abstract

Healthy ear canal skin has an acidic pH. Evidence suggests that reacidifi cation of the ear canal may lead to resolution of otitis externa. Th e pH of 15 commonly prescribed topical ear drop preparations used in the treatment of otitis externa was measured using a Jenway 3020 pH meter with temperature compensation at 37.5°C. Th e pH values ranged from 2.89 to 7.83. Two-thirds of preparations tested were of acidic pH. Th e remaining one-third were alkaline. Reacidifi cation of the ear canal may help in the treatment of otitis externa.

Manufacturability of a Tetraethyl Orthosilicate-Based Hydrogel for Use as a Single Application Otitis Externa Therapeutic

“…There are two main factors in the outer ear that may impact the release of drugs from these hydrogels: ear pH and the presence of factors/enzymes that depolymerize HA. The pH of the ear is usually acidic, and becomes more neutral when the ear is infected, ranging from 7.1 to 7.8 [ 25 , 26 ]. As a result, we wanted to investigate the impact of pH on the drug release from the gels.…”

“…Finally, we investigated the impact of two application specific physiological factors, specifically local pH and enzymatic activity, on drug release from the hydrogels. The pH of the ear varies widely, with a healthy ear typically having an acidic pH, and an infected ear having a pH from 7.1 to 7.8 [ 25 , 26 ]. The drug release from the hydrogels into PBS with a pH of 7.6 was not significantly different from the release into PBS with a pH of 4.0, indicating that patient ear pH would not impact the efficacy of the treatment ( Table S7 ).…”

A Recent Overview of Locally Administered Topical Otic Dosage Forms

“…Generally, topical otic preparations are prepared in the form of acidic solutions or suspensions with a pH of 3-4 for inhibition of bacterial growth. Commonly used excipients are summarized in Table 1, based on the FDA inactive content database and on the market-approved current otic products 17,18 . In the development of otic formulations physicochemical factors such as solubility, viscosity, tonicity, surfactant and preservative properties, serum diffusion activity, impregnation properties, serumolytic activity and rheological properties play an important role 19 .…”