Upon completion of this exercise, you should be able to:
- Identify the external part of the ear where compounded formulations are placed.
- Identify common nonaqueous vehicles used in otic formulations.
- Identify common ointment bases used in otic formulations.
The ear has three main sections: the outer ear, the middle ear, and the inner ear. The outer ear contains the external part of the ear as well as the part of the ear canal that leads up to the tympanic membrane. Cerumen (ear wax) is produced in the skin of the ear canal. It serves to lubricate the canal and extrap dust and foreign materials.
The middle ear contains the three ear bones or ossicles: the malleus, incus, and stapes. The middle ear also contains the Eustachian tube. The Eustachian tube functions to equalize pressure and allows mucus drainage.
The inner ear contains the cochlea which is the organ of hearing. The inner ear also contains three semi-circular canals and the vestibule which function to maintain balance.
The external auditory canal provides an ideal environment for bacterial growth because it is warm and moist. Otic solutions and suspensions are used to treat infections in the external auditory canal. The solvents are typically glycerin, propylene glycol, vegetable oils (e.g., olive oil), mineral oils, or low molecular weight polyethylene glycols (e.g., PEG 300). These solvents adhere to the canal wall better than water or alcohol.
A formulation for ear wax impaction could contain carbamide peroxide, glycerin, hydrogen peroxide, and olive oil. The carbamide peroxide and hydrogen peroxide contribute a mechanical “bubbling” action that softens and breaks up dried cerumen. These two ingredients also have anti-infective properties.
Glycerin is hygroscopic and absorbs moisture which also helps soften cerumen. Olive oil is a softening agents and keeps the formulation in the ear longer because of its viscosity.
The itching associated with seborrhea, or psoriasis, can be treated with topical corticosteroid formulations. Otic gels and ointments are used in these formulations and they are applied directly to the skin of the ear. Otic ointments typically use petrolatum as the base.
Otic Drop Administration
- Wash your hands with soap and warm water.
- Warm the dropper bottle in your hands. If a suspension, shake well prior to withdrawing medication.
- Draw up a small amount of medication into the medicine dropper.
- Lie on your side so that the affected ear points toward the ceiling.
- Position the tip of the medicine dropper just inside the affected ear canal. Avoid touching the dropper against the ear or anything else. For adults, hold the ear lobe up and back; for children, hold the earlobe down and back.
- Squeeze the directed number of drops into ear canal and allow the drops to run into the ear.
- Remain lying down for 3 to 5 minutes so that the medication has a chance to spread throughout the ear canal; gently massage the area around ear to aid the spreading and distribution of the ear drops in the canal.
- Place a clean cotton pledget just inside ear to prevent leakage of the solution when head is held in an upright position.
- Replace the cap tightly on the bottle.
- Never use ear drops if your eardrum has been damaged.
- Avoid using very hot or very cold ear drops. The medication should be at room temperature or slightly warmer. If necessary, warm the drops by holding the bottle in your hand for a few minutes.
- It may be much easier to have someone else instill ear drops if this is easier for you.