NEOSTIGMINE (Prostigmine)
Chemistry:
It is a synthetic quaternary ammonium compound.
Pharmacokinetics
Being a quaternary ammonium compound, it is irregularly absorbed from GIT and it cannot cross the B.B.B.
Pharmacodynamics
Mechanism of Action
- Reversible inhibition of cholinesterase enzymes (Muscarinic effects and Nicotinic effects ).
- Direct stimulant action on neuromuscular junctions.
- It has no CNS effects.
Therapeutic Uses
- Treatment and diagnosis of myasthenia gravis: S.C for diagnosis Oral for treatment; a condition which causes abnormal weakness of muscles
- Antidote to D-tubocurarine.
- Treatment of postoperative retention of urine.
- Treatment of paralytic ileus.
Untoward Effects
All the muscarinic and nicotinic effects except that intended for therapeutic purposes.
NEOSTIGMINE SUBSTITUTES (Pyridostigmine, Ambenonium )
Neostigmine substitutes have been introduced with the advantage of being more selective on the neuromuscular junction or having a longer duration of action to be more convenient for the treatment of myasthenia gravis and other clinical purpose.
a- Pyridostigmine
b- Ambenonium : Similar to pyridostigmine.
c- Edrophonium; More selective on NMJ than neostigmine. - Very short acting (5 min.)
More selective on NMJ than neostigmine. Very short acting (5 min.) Uses
- Diagnosis of myasthenia gravis.
- Treatment of myasthenic crisis.
- Differentiation between myasthenic crisis and cholinergic crisis Antidote for D-tubocurarine.