Pilocarpine

Pilocarpine belongs (like carbachol and betanechol) to the group of direct parasympathomimetics. Pilocarpine is an imidazole alkaloid with the molecular formula: C11H16N2O2 and a molar mass of 208.26 g-mol-1.

Pilocarpine occurs naturally in leaves of Pilocarpus species, e.g. Pilocarpus jaborandi or Pilocarpus pennatifolius or Pilocarpus racemosus, shrubs native to northern Brazil. Pilocarpus jaborandi contains 0.6%-0.7% pilocarpine, as well as pilocarpidin (oil) and isopilocarpine.

As a muscarinic receptor agonist, and thus as a direct-acting parasympathomimetic, pilocarpine increases the secretion of exocrine glands (sweat, saliva, tears, stomach, pancreas and intestinal glands) and the production of mucus by the goblet cells in the respiratory tract. It also increases the tone of smooth muscles and the sphincter pupillae.

Warning: Symptoms of pilocarpine poisoning by accidental ingestion are hypersalivation, lacrimation, nasal secretion, nausea, vomiting, diarrhea, tenesmus vesicalis, pupil constriction, accommodation spasm, palpitations, arrhythmias, convulsion, tremors and dyspnea.

In ophthalmology, pilocarpine is used as a local therapeutic agent, especially for acute angle block glaucoma (acute glaucoma) (1-2% solution). Pilocarpine leads to miosis (contraction of the muscle sphincter pupillae) and to an increased outflow of aqueous humor by widening the angle of the chamber and opening the outflow pathways, which reduces the intraocular pressure.

Another area of application is radiation-induced dry mouth(xerostomia). A 0.1% pilocarpine gel or pilocarpine tablets are used. Another indication is xerostomia in Sjögren's syndrome.

Pilocarpine oil kills crabs by inhibiting their breathing. It can therefore be used for the treatment of phthiriasis palpebrarum.

Furthermore, the substance is used in the "pilocarpine iontophoresis sweat test" to diagnose cystic fibrosis.

Pilocarpine was discovered and isolated in 1875 by E. Hardy in France and A. W. Gerrard in London.

1. Roth L et al (1984) Poisonous plants, plant toxins. Pilocarpus jaborandi S.566
2. Graefe KH (2016) Aotonome nervous system. In: Graefe KH et al (Eds) Pharmacology and Toxicology. Georg Thieme Publisher S 109-110