Myasthenia gravis cholinesterase inhibitors

Myasthenia gravis Cholinesterase inhibitors, immunosuppressants Weakness, fatiguability, diarrhea, drooling, CBC and infections (immunosuppressants)... 

The cholinesterase inhibitor that is used in the diagnosis of myasthenia gravis is... 

Because anticholinesterase agents also inhibit plasma pseudo-ChE, they will potentiate the effects of succinylcholine by inhibiting its breakdown. This is important, for example, when succinylcholine is to be employed in patients who have previously received cholinesterase inhibitors for the treatment of myasthenia gravis or glaucoma. 

Mechanism of Action A cholinesterase inhibitor that enhances and prolongs cholinergic function by increasing the concentration of acetylcholine through inhibition of f he hydrolysis of acefylcholine. Therapeutic Effect Increases muscle strength in myasthenia gravis. 

The major therapeutic uses of the cholinomimetics are for diseases of the eye (glaucoma, accommodative esotropia), the gastrointestinal and urinary tracts (postoperative atony, neurogenic bladder), the neuromuscular junction (myasthenia gravis, curare-induced neuromuscular paralysis), and very rarely, the heart (certain atrial arrhythmias). Cholinesterase inhibitors are occasionally used in the treatment of atropine overdosage. Several newer cholinesterase inhibitors are being used to treat patients with Alzheimer s disease. 

Edrophonium is also used to assess the adequacy of treatment with the longer-acting cholinesterase inhibitors in patients with myasthenia gravis. If excessive amounts of cholinesterase inhibitor have been used, patients may become paradoxically weak because of nicotinic depolarizing blockade of the motor end plate. 

As mentioned in Part 2, there are drugs that can interfere with the inactivation of neurotransmitters. In that particular case the reversible cholinesterase inhibitor neostigmine was discussed within the context of treating myasthenia gravis. Excessive blockade of acetylcholinesterase at both muscarinic and nicotinic synapses results in a sustained excess of acetylcholine, which persistently activates the effector they innervate. Muscarinic stimulation results in excessive salivation, lacrimation, bronchiolar secretions, and bronchoconstriction. Nicotinic stimulation produces effects such as those described earlier for nicotine. 

Pyridostigmine [peer id doe STIG meen] is another cholinesterase inhibitor that is used in the chronic management of myasthenia gravis. Its duration of action (3-6 hours) is longer than that of neostigmine (2-4 hours). 

The pharmacologic treatment of myasthenia gravis is based on increasing the amount of available acetylcholine by use of oral cholinesterase inhibitors such as neostigmine or pyridostigmine. Pyridostigmine bromide (Mestinon) is used most often and effectively relieves myasthenic symptoms in small muscles innervated by cranial nerves, particularly those involved in ptosis. 

Plasmapheresis is an intermediate form of therapy for myasthenia gravis, having effects that last longer than those of cholinesterase inhibitors but shorter than those of thymectomy. Improvement in myasthenic symptoms often occurs, but its duration is unpredictable. Plasmapheresis usually is reserved for patients who have severe symptoms resistant to other therapeutic approaches or for patients preparing for thymectomy. 

Trade names Enlon (Baxter) Tensilon (Valeant) Indications Myasthenia gravis diagnosis Category Anesthetic Cholinesterase inhibitor Half-life 1.8 hours... 

Use of NLO likely improves response and reduces systemic adverse effects and should be performed by all patients administering cholinesterase inhibitors. These agents should be used with caution in patients with asthma, retinal detachments, narrow angles, bradycardia, hypotension, heart failure, Down s syndrome, epilepsy, parkinsonism, peptic ulcer, and ocular inflammation, as well as in those receiving cholinesterase inhibitor therapy for myasthenia gravis or exposure to carbamate or organophosphate insecticides and pesticides. ... 

Ambenonium, a cholinesterase inhibitor (5 to 25 mg p.o. t.i.d.), is indicated in the symptomatic treatment of myasthenia gravis. Ambenonium results in accumulation of acetylcholine-stimulating cholinergic receptors at the myoneural junction (see Figure 12). 

Pyridostigmine, a cholinesterase inhibitor, is used as an antagonist for curariform paralysis and in myasthenia gravis. 

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