Action And Clinical Pharmacology: Neostigmine inhibits the destruction of acetylcholine by cholinesterase, thus permitting freer transmission of nerve impulses across the neuromuscular junction. It also has a direct effect on voluntary muscle fibres and possibly on autonomic ganglion cells and neurons of the CNS.
After absorption or i.v. administration, 80% of a dose is excreted by the kidney in the unchanged (50%) and metabolized (30%) forms in 24 hours. The elimination half-life is approximately 51 to 91 minutes.
Indications And Clinical Uses: Ampuls: Prophylaxis and treatment of postoperative intestinal atony, urinary retention; in serious cases of myasthenia gravis; to neutralize effect of curare in surgical anesthesia and shock therapy.
Tablets: Myasthenia gravis.
Contra-Indications: Bronchial asthma or mechanical obstruction of intestinal or urinary tract. Known hypersensitivity to neostigmine.
Precautions: When large doses are given, simultaneous administration of atropine sulfate may be advisable. Because of the possibility of hypersensitivity in an occasional patient, atropine should always be at hand, together with antishock medications. Hypotension and bradycardia may occur if the effect of gallamine or curare is antagonized by neostigmine.
Adverse Reactions: The untoward effects of neostigmine are most commonly related to overdosage and generally are of two varieties: muscarinic and nicotinic. Among the former group are nausea, vomiting, diarrhea, abdominal cramps, increased salivation, increased bronchial secretions, miosis, and diaphoresis. Muscarinic untoward effects can usually be counteracted by atropine. Nicotinic untoward effects are chiefly muscle cramps, fasciculation and weakness, which can be difficult to distinguish from exacerbation of underlying myasthenia gravis.
Symptoms And Treatment Of Overdose: Symptoms: Muscarinic and nicotinic effects (see Adverse Effects). Distinguish from myasthenic crisis with edrophonium chloride, if necessary.
Treatment: Control muscarinic effects with i.v. atropine, followed by i.m. atropine every 2 to 4 hours. Assist ventilation and treat convulsions or shock if necessary.
Dosage And Administration: Intestinal Atony, Postoperative: Prophylaxis: 250 µg s.c. or i.m. before or immediately after operation, repeated every 4 to 6 hours s.c. Treatment: 500 µg (1 mL 1:2 000) s.c., i.m. (or possibly i.v.) repeated at intervals of 4 to 5 hours.
Urinary Retention: Prophylaxis: 250 µg (1 mL 1:4 000) as for intestinal atony. Treatment: 500 µg (1 mL 1:2 000) s.c. or i.m. and apply heat to the lower abdomen. If urination does not occur within one hour, the patient should be catheterized. After the patient has voided, continue the 500 µg injections at 3-hour intervals for at least 5 additional injections.
Myasthenia Gravis: 75 to 300 mg orally, spaced over 24 hours as required. Occasionally parenteral therapy is needed in seriously ill patients and up to 1 mg i.m. every hour may be necessary in myasthenic crises.
Curare Antagonist (to neutralize the effect of curare in surgical anesthesia and shock therapy): 0.5 to 2 mg i.v. Atropine sulfate 0.6 to 1.2 mg i.v. should also be given.
Availability And Storage: Injections: Prostigmin 1:2 000: Each mL contains: neostigmine methylsulfate 0.5 mg (500 µg) and sodium hydroxide to adjust pH to 5.9. Each mL of ampul solution also contains 1.8 mg methylparaben and 0.2 mg propylparaben as preservatives. Alcohol- and sulfite-free. Each mL of vial solution contains 4.5 mg phenol as preservative and sodium acetate and acetic acid as buffer. Paraben-, and sulfite-free. Vials of 10 mL. Packs of 10.
Prostigmin 1:1 000: Each mL contains: neostigmine methylsulfate 1 mg, with 4.5 mg phenol as preservative, sodium acetate and acetic acid as buffer and sodium hydroxide to adjust pH to 5.9. Paraben- and sulfite-free. Vials of 10 mL, packs of 10.
Prostigmin 1:400: Each mL contains: neostigmine methylsulfate 2.5 mg, with 4 mg phenol as preservative, sodium chloride for isotonicity and sodium hydroxide to adjust pH to 6.0. Paraben- and sulfite-free. Vials of 5 mL, packs of 5 and 10.
Tablets: Each white, cylindrical, biplane tablet with bevelled edges, single-scored on one side, contain: neostigmine bromide 15 mg. Also contains lactose 150 mg. Energy: 3.5 kJ (0.8 kcal). Gluten-, paraben-, sodium-, sulfite- and tartrazine-free. Bottles of 100.
Store injections at 15 to 30°C and protect from light. Protect tablets from excessive heat (40°C), and keep in a tightly closed container.
PROSTIGMIN® Preparations ICN Neostigmine Parasympathomimetic
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