Neostigmine 15mg Tablets: UK Dosing Information
Neostigmine 15mg tablets are available in the UK, but there is no established evidence-based dosing regimen for oral neostigmine tablets in standard clinical practice, as this formulation is rarely used and lacks robust clinical guidelines.
Critical Context
The evidence base for oral neostigmine is extremely limited. The available literature focuses almost exclusively on:
- Intravenous neostigmine for reversal of neuromuscular blockade in anaesthesia (standard dose 0.04-0.05 mg/kg IV) 1, 2
- Oral pyridostigmine as the preferred anticholinesterase for chronic conditions like myasthenia gravis 3
Conversion Considerations (Use with Extreme Caution)
If oral neostigmine must be used, the only available conversion reference suggests:
- 30 mg oral pyridostigmine ≈ 1 mg IV neostigmine 3, 4
- This ratio applies to parenteral neostigmine only, not oral formulations 3
Important caveat: This conversion does not account for the bioavailability differences between oral and IV neostigmine, making direct extrapolation unreliable and potentially dangerous 3.
Clinical Management Recommendations
If switching from pyridostigmine to oral neostigmine is absolutely necessary:
- Must be done under direct neurologist supervision with frequent clinical monitoring 3
- Start with conservative dosing and titrate based on clinical response 3
- Monitor intensively for cholinergic side effects including increased salivation, lacrimation, diarrhea, urinary urgency, sweating, and bradycardia 3
Alternative Evidence: Intranasal Administration
One small study demonstrated that intranasal neostigmine can substitute for morning doses of oral pyridostigmine in myasthenia gravis patients, with effects occurring in 5-15 minutes 5. However, this route differs significantly from oral tablet administration.
Safety Concerns with Neostigmine
Therapeutic doses of neostigmine can paradoxically cause muscle weakness:
- IV neostigmine 35 μg/kg (approximately 2.5 mg) caused 20% reduction in grip strength and restrictive spirometry pattern in healthy volunteers 6
- A second dose further decreased grip strength by 41% 6
- These effects result from depolarizing neuromuscular blockade 6
Standard Practice Recommendation
Pyridostigmine remains the evidence-based oral anticholinesterase of choice:
- Standard dosing: 30-60 mg orally three times daily, gradually increasing to maximum 120 mg four times daily as needed 3
- This has decades of established safety and efficacy data 3
Bottom Line
Without established dosing guidelines, pharmacokinetic data, or safety studies for oral neostigmine 15mg tablets, any use should be considered off-label and undertaken only with specialist supervision, starting at the lowest possible dose with intensive monitoring for both therapeutic effect and cholinergic toxicity 3.