**2. Anticholinergics**

Ipratropium bromide is an anticholinergic compound related to atropine. It is poorly absorbed, but has high topical activity. It inhibits secretion for at least 4 hours, without the appearance of systemic symptoms.

Mechanism of action: It is capable of significantly reducing rhinorrhoea by acting selectively on the muscarinic receptors, which, when activated by acetylcholine released by the parasympathetic nervous system, induce the secretion of mucus by the nasal seromucous glands.

Systemic cholinergic collateral effects rarely appear, but include changes in vision, tachycardia, urinary retention and dry mouth. However, it should be administered with caution to patients with glaucoma or prostatic hypertrophy.

Ipratropium bromide is used in aqueous solution for topical nasal use in doses of two inhalations of 0.02 mg each three times a day in each nostril. The recommended dose should not be increased if there is no improvement.

It has been used for allergic (Kaiser et al, 1995) and non-allergic (Bronsky et al, 1995) perennial rhinitis, and acts by improving hydrorrhoea, with a maximum peak 1-4 hours after administration. It has barely any effect on nasal obstruction and sneezing, and its most frequent side effects are epistaxis, nasal dryness and headache (Kaiser et al, 1995; Bronsky et al, 1995).
