These are solutions that are instilled into the ear with a dropper. The solution is generally prepared in water, glycerin or propylene glycol. Ear drops are generally used for cleaning the ear, softening the wax and treating mild infections. However, this may cause inconvenience to patients because they have to lie down or tilt their head at angle of 45° when ear drops are administered. The important consideration in the formulation of ear drops is the selection of vehicle. The vehicle should mix easily with ear wax and should make maximum contact between the drug and the tissues of the ear. Anhydrous glycerin and propylene glycols are the commonly used vehicles. These vehicles remove the moisture from the tissue, thereby reducing the growth of microorganisms and inflammation. For the purpose of preservation, preservatives such as chlorobutanol and thiomersal are employed in the formulation. The commonly used medicaments in ear drops include anti-infectives, wax softener, antiseptics, astringents and anti-inflammatory agents.

Example

Sodium bicarbonate ear drops BP

Sodium bicarbonate is dissolved in water. To this, glycerin is added and mixed well. Glycerin provides the softening capacity to the solution and it reduces itching due to its emollient property. To this solution, the remaining quantity of water is added and the required volume is made up.