The rapid administration of lifesaving medications in situations of overdose or epilepsy is of indisputable importance in the prehospital and Emergency Department (ED) settings. Decreasing the time to analgesia for children and adults with painful conditions is a clear priority and the intranasal administration of medications is ideal. It is an important tool for the Emergency Physician to have in their armamentarium. The intranasal administration of medications for anxiolysis in children and adults may limit the need for painful intravenous (IV) line insertion or intramuscular (IM) administration. The old method of dripping the medication from a syringe was not effective. Most of the medication ran into the nasopharynx, was swallowed, and resulted in erratic absorption. Atomizers are now inexpensive, single use, and available in many EDs.
ANATOMY AND PATHOPHYSIOLOGY
The normal physiologic function of the nasal cavities is to warm, humidify, and partially filter outside air. The qualities that make the nose effective physiologically also make it an ideal site for drug administration. The nose has a large surface area of approximately 160 cm2 with a thin permeable barrier that is 2 to 4 mm thick and an extensive capillary network.1 The blood flow to nasal mucosa per cubic centimeter of tissue is greater than brain, liver, or muscle tissue.2 The large mucosal surface with its rich vascular bed provides for excellent absorption and drug bioavailability. Relatively lipid-soluble drugs are rapidly and reliably absorbed without the first-pass metabolism of taking medications orally.2
Atomized medication delivery improves bioavailability by increasing mucosal coverage and decreasing the amount of medication lost to swallowing. The maximum absorption is reported for doses of 0.15 mL per nostril.2 The recommended maximum volume is less than 1 mL per nostril for adults and 0.3 mL per nostril for pediatric patients. Medication may need to be divided into multiple smaller doses to maximize efficacy and minimize patient discomfort. Using a more concentrated formulation of a medication may decrease the number of doses required. Using both nostrils improves absorption.3
The intranasal administration of medications is indicated for certain medications when rapid delivery is desired. It is also indicated for patients with limited or difficult vascular access. An additional benefit is the avoidance of painful IV line insertion attempts or IM injections. The advantages and disadvantages of intranasal medication are listed in Table 201-1. It can be used prior to many ED procedures (Table 201-2). The indications and dosing for medications commonly given by the intranasal route are listed in Table 201-3.1-54 The specific characteristics of each medication is noted in Chapter 12.
TABLE 201-1The Advantages and Disadvantages of Intranasal Medication Administration