Formulation in Pharmacy Practice  - eMixt

Verapamil
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Verapamil hydrochloride is soluble in water, 1 in 20, with a bitter taste.
Aqueous solutions of 0.5mg per mL are reported to be very stable and the optimum pH range for stability is 3.2 - 5.6.1
The injection, 2.5mg per mL, has a pH of 4.1 - 6.  Precipitation may occur in solutions having a pH of greater than 6.  If small doses are required it is practical to give the injection orally.

A New Zealand standardised formula is available Formula and Batch Sheet
This formula uses Ora-Blend/SF or Ora-Plus and Ora-Sweet/SF in equal parts, and has been approved by the Extemporaneous Compounding Pharmacists' Group.

Verapamil hydrochloride 50mg per mL, prepared from tablets in a 1:1 mixture of Ora-Sweet and Ora-Plus, or a 1:1 mixture of Ora-Sweet SF and Ora-Plus or Cherry Syrup was stable for up to 60 days at 5°C or 25°C, protected from light.2   The final pH of these preparations was in the range 3.4 - 4.4.

If these commercial bases are unavailable the following formula is suggested based on a review of the literature.


Formula

Verapamil oral liquid
 
Verapamil tablets qs 
Syrup 10  mL
Glycerol 40  mL
Parabens 0.1  %
Water to   100  mL
If possible check the pH.  If the pH is > 5 add a small amount of citric acid to bring within the range of pH 4 - 5.
Expiry:  30 days
Storage:  Refrigerate.  Protect from light (amber container)
Shake well before use
 

 
References
  1. Das Gupta V.  Quantitation and stability of verapamil hydrochloride using high-performance liquid chromatography.  Drug Dev Ind Pharm 1985; 11 (8): 1497-1506.
  2. Allen L.V., Erickson M.A.  Stability of labetalol hydrochloride, metoprolol tartrate, verapamil hydrochloride and spironolactone with hydrochlorothiazide in extemporaneously compounded oral liquids. Am J Health-Syst Pharm 1996; 53: 2304-9.

 
Formulation in Pharmacy Practice
Page Updated  March 2014