Nasal administration

Nasal sprays are locally acting drugs such as decongestants for cold and allergy treatment, whose systemic effects are usually minimal.

[2] Sharing snorting equipment (nasal spray bottles, straws, banknotes, bullets, etc) has been linked to the transmission of hepatitis C. In one study, the University of Tennessee Medical Center researchers warned that other blood-borne diseases such as HIV could be transmitted as well.

[5] Therefore, a drug molecule can be transferred quickly across the single epithelial cell layer directly to the systemic blood circulation without first-pass hepatic and intestinal metabolism.

Other potential drug candidates for nasal administration include anaesthetics, antihistamines (Azelastine), antiemetics (particularly metoclopramide and ondansetron) and sedatives that all benefit from a fast onset of effect.

Recently, the upper part of the nasal cavity, as high as the cribriform plate, has been proposed for drug delivery to the brain.

Intranasal oxytocin is also being actively investigated for many psychiatric conditions including alcohol withdrawal, anorexia nervosa, PTSD, autism, anxiety disorders, pain sensation and schizophrenia.

Snuff trays and tubes similar to those commonly used for yopo were found in the central Peruvian coast dating back to 1200 BC, suggesting that insufflation of Anadenanthera beans is a more recent method of use.

[26] The major part of the approximately 150 cm2 surface in the human nasal cavity is covered by respiratory epithelium, across which systemic drug absorption can be achieved.

The transfer of drugs to the brain from the blood circulation is normally hindered by the blood–brain barrier (BBB), which is virtually impermeable to passive diffusion of all but small, lipophilic substances.

[27][28] Olfactory transfer could theoretically be used to deliver drugs that have a required effect in the central nervous system such as those for Parkinson's or Alzheimer's diseases.