Pyridostigmine

Pharmaceuticals

Pharmaceuticals -> Listed in ZINC15

Breast Feeding; Lactation; Milk, Human; Cholinesterase Inhibitors; Parasympathomimetics

Pharmaceuticals

Medicines for myasthenia gravis

152-154

153 °C

If the compound has been ingested, rapid gastric lavage should be performed using 5% sodium bicarbonate. For skin contact, the skin should be washed with soap and water. If the compound has entered the eyes, they should be washed with large quantities of isotonic saline or water. In serious cases, atropine and/or pralidoxime should be administered. Anti-cholinergic drugs work to counteract the effects of excess acetylcholine and reactivate AChE. Atropine can be used as an antidote in conjunction with pralidoxime or other pyridinium oximes (such as trimedoxime or obidoxime), though the use of '-oximes' has been found to be of no benefit, or possibly harmful, in at least two meta-analyses. Atropine is a muscarinic antagonist, and thus blocks the action of acetylcholine peripherally.

Acute exposure to cholinesterase inhibitors can cause a cholinergic crisis characterized by severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Accumulation of ACh at motor nerves causes overstimulation of nicotinic expression at the neuromuscular junction. When this occurs symptoms such as muscle weakness, fatigue, muscle cramps, fasciculation, and paralysis can be seen. When there is an accumulation of ACh at autonomic ganglia this causes overstimulation of nicotinic expression in the sympathetic system. Symptoms associated with this are hypertension, and hypoglycemia. Overstimulation of nicotinic acetylcholine receptors in the central nervous system, due to accumulation of ACh, results in anxiety, headache, convulsions, ataxia, depression of respiration and circulation, tremor, general weakness, and potentially coma. When there is expression of muscarinic overstimulation due to excess acetylcholine at muscarinic acetylcholine receptors symptoms of visual disturbances, tightness in chest, wheezing due to bronchoconstriction, increased bronchial secretions, increased salivation, lacrimation, sweating, peristalsis, and urination can occur. Certain reproductive effects in fertility, growth, and development for males and females have been linked specifically to organophosphate pesticide exposure. Most of the research on reproductive effects has been conducted on farmers working with pesticides and insecticdes in rural areas. In females menstrual cycle disturbances, longer pregnancies, spontaneous abortions, stillbirths, and some developmental effects in offspring have been linked to organophosphate pesticide exposure. Prenatal exposure has been linked to impaired fetal growth and development. Neurotoxic effects have also been linked to poisoning with OP pesticides causing four neurotoxic effects in humans: cholinergic syndrome, intermediate syndrome, organophosphate-induced delayed polyneuropathy (OPIDP), and chronic organophosphate-induced neuropsychiatric disorder (COPIND). These syndromes result after acute and chronic exposure to OP pesticides.

N07AA02

N - Nervous system

QN - Nervous system

N07AA02

Pyridostigmine bromide, designated as 3-hydroxy-1-methyl-pyridinium bromide dimethyl-carbamate, is an orally active reversible cholinesterase inhibitor similar to [neostigmine] but with a milder adverse effect profile and a longer duration of action. Pyridostigmine may, specifically in the case of excessive administration, result in a cholinergic crisis, with symptoms mimicking a myasthenic crisis. Administration of atropine is recommended in the case of a true cholinergic crisis or to counteract muscarinic/nicotinic effects such as bradycardia and excessive bronchial secretions.

Myasthenia gravis is an autoimmune disease involving dysfunction at the neuromuscular junction most commonly due to autoantibodies directed against the acetylcholine receptor (AChR), but also against other targets such as the muscle-specific kinase (MUSK), lipoprotein-related protein 4 (LRP4), or agrin. In the case of AChR antibodies, AChRs are directly bound and cross-linked, impairing acetylcholine binding and contributing through various mechanisms to receptor degradation. The lack of acetylcholine signalling leads to muscle tone loss, muscle weakness, and fatigue. Pyridostigmine is a reversible acetylcholinesterase inhibitor that increases extracellular acetylcholine levels in the neuromuscular junction by impairing its breakdown by acetylcholinesterase. The increased acetylcholine leads to increased neural transmission across the junction, which drastically improves myasthenia gravis symptoms. In addition to its use in myasthenia gravis and in reversing neuromuscular blocks, pyridostigmine is also a common first-line treatment in congenital myasthenic syndromes (CMS), of which there are multiple subtypes caused by mutations in more than 30 distinct genes. CMS present similarly to myasthenia gravis, albeit due to distinct underlying causes, and often benefit from pyridostigmine. However, in some subgroups, treatment with pyridostigmine is detrimental; detailed genetic testing is required before starting therapy.