Pyridostigmine
Mechanism :
Pyridostigmine is a cholinergic agent which acts primarily by the inhibition of cholinesterase. It enhances cholinergic action by facilitating the transmission of impulses across neuromuscular junctions. It also has a direct cholinomimetic effect on skeletal muscle and possibly on autonomic ganglion cells and neurons of the CNS. Because of its quaternary ammonium structure, moderate doses of pyridostigmine do not cross the blood-brain barrier to produce CNS effects.
Indication :
- Myasthenia gravis
- Reversal of non-depolarizing muscle relaxant
Contraindications :
In patients with known hypersensitive to anticholinesterase agents. Because of the presence of the bromide ion, this product should not be used in patients with a prior history of reaction to bromides. It is also contraindicated in patients with peritonitis or mechanical obstruction of the intestinal or urinary tract.
Dosing :
Myasthenia gravis:
Neonates: 5 mg PO every 4-6 hours or 0.05-0.15 mg/kg IV/IM every 4-6 hours; Maximum dose: 10 mg/dose.
Children: 7 mg/kg/day PO in 4 hourly divided doses or 0.05-0.15 mg/kg IV/IM every 4-6 hours; Maximum dose: 10 mg/dose.
Reversal of non-depolarizing muscle relaxants:
0.1-0.25 mg/kg/dose IV. Full recover may occur in <15 mins but may require >30 mins also.
Adverse Effect :
Increased salivation, fasciculation, abdominal cramps, diarrhea, increased bronchial secretions, nausea, vomiting, increased peristalsis, muscle cramps, urticaria, rash, miosis, diaphoresis, weakness, allergic reactions.
Interaction :
Atropine: Antagonizes the muscarinic effects of pyridostigmine and this interaction may be utilized to counteract the effects of pyridostigmine.
Succinylcholine or Decamethonium: Pyridostigmine does not antagonize, and in fact may prolong the phase I block of depolarizing muscle relaxants such as succinylcholine or decamethonium.
Neomycin, Streptomycin and Kanamycin: Have a mild but definite nondepolarizing blocking action which may accentuate neuromuscular block. These antibiotics should be used in the myasthenic patient only where definitely indicated, and then careful adjustment should be made of adjunctive anticholinesterase dosage.
Local and some General Anesthetics, Antiarrhythmic Agents and other drugs that interfere with Neuromuscular Transmission: Should be used cautiously, if at all, in patients with myasthenia gravis.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-30 | 35% of daily dose |
| 10-20 | 35% of daily dose |
| <10 | 20% of daily dose |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unknown dialysability. Dose as in GFR<10 mL/min |
| HD | Unknown dialysability. Dose as in GFR<10 mL/min |
| HDF/High flux | Unknown dialysability. Dose as in GFR<10 mL/min |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
No dose adjustment recommended.