Formulation in Pharmacy Practice   2nd Edition

Dantrolene is a weak acid with a pKa of about 7.5.
Dantrolene sodium is slightly soluble in water but free dantrolene tends to precipitate out of solution especially in acidic conditions.  Sodium hydroxide is included in the formulation of the injection to give a pH after reconstitution of about 9.5.
Reconstituted dantrolene sodium injection is reported to be stable for only 6 hours at 15 - 30°C.
The injection would be considered too expensive to give orally.


Dantrolene 25mg per 5mL suspension
Dantrolene sodium capsules 100mg  
Citric acid monhydrate 150  mg
Water 10  mL
Syrup BP (preserved) to   100  mL
(Any preserved syrup would be suitable)    
Storage:  Room temperature preferable to give better dose uniformity.
Shake before use:   Very important as dantrolene is in suspension.

  1. Use of an alternative suspending vehicle e.g. methylcellulose could be investigated.
  2. If unpreserved syrup is used a 7 day expiry is suggested.

  1. Fawcett J.P., Stark G., Tucker I.G., Woods D.J.  Stability of dantrolene oral suspension prepared from capsules.  J Clin Pharm Ther 1994; 19 (6): 349-53.

Formulation in Pharmacy Practice
2nd Edition