How do they work?
By producing vasoconstriction in the nasal sinusoids, which are regulated by adrenergic-type mechanisms, specifically by α-receptors. Three (3) types may be identified:
- α1 (post-synaptics): particularly sensitive to the release of noradrenalin by the sympathetic nerve fibres. Phenylephrine and Methoxamine are α1-adrenergic receptor agonists. Phenylephrine is very seldom used because it may cause hypertension and reflex bradycardia.
- α2 (pre-synaptics): responsible for inhibitory retrocontrol of noradrenalin release. α2-adrenergic receptor agonists like methoxamine have a more powerful, longer lasting and selective effect.
- α2 (post-synaptics): sensitive to the adrenaline produced by the adrenal medulla of the suprarenal capsules. The agonists of these receptors are derived from clonidine, such as Oxymetazoline, Xylometazoline, and Naphazoline, have a slow but prolonged onset of action and are the most frequently used.
- What should be recommended for their proper use?
What situations may give rise to problems related to these medicinal products?
- Clean the nose before every application.
- Administer with the head upright, breathing in deeply.
- Do not use for more than 3-5 days to avoid the rebound effect.
Do these drugs interact with other medicinal products?
- There may be a worsening in the conditions of diabetic and hypertensive patients with glaucoma, heart diseases and hyperthyroidism.
- Warn the patient about driving and the use of machinery since these drugs may cause drowsiness.
- No interactions have been described for Naphazoline, Oxymetazoline, Xylometazoline or Tramazoline.