Formulation in Pharmacy Practice   2nd Edition

PROPRANOLOL
 
 
Propranolol is soluble in water and alcohol with a bitter taste.  Injections have a pH of 2.8 - 3.5.
Solutions of propranolol hydrochloride have optimum stability at about pH 3 and decomposition is rapid at alkaline pH.
Oral liquids are commercially available in some countries.

Formula A is based on manufacturer's recommendations and stability studies.1  Formula B is a simpler alternative based on published stability studies1,2,4 and evaluation of the literature.

Formula A

Propranolol Oral Liquid
 
Propranolol tablets qs   
Sodium carboxymethylcellulose g
Sodium citrate 0.21  g
Citric acid monohydrate 0.28  g
Syrup BP 25  mL
Parabens 0.1  %
Water to   100  mL
 
Expiry:  30 days
 
Storage:  Refrigerate.  Protect from light.
 
Shake well before use
 

 
Formula B

Propranolol Oral Liquid 5mg per mL
 
Propranolol tablets 40mg 12.5   
Citric acid monohydrate g
Parabens 0.1  %
Syrup or Glycerol 40  mL
Water to   100  mL
 
Expiry:  30 days
 
Storage:  Refrigerate.  Protect from light.
 
Shake well before use
 

 
NOTES
  1. The extraction of propranolol hydrochloride from Inderal® tablets and probably other brands is pH dependent being most efficient at low pH.2  Filtering out tablet excipients without acid extraction may remove significant amounts of propranolol.  In the above formulations tablets should be ground and mixed with some of the citric acid in solution to improve extraction.
  2. Sodium benzoate 0.1 - 0.2% could be used instead of parabens.
Other Formulations
  1. A 1mg per mL oral liquid prepared from propranolol tablets and Roxane® diluent was reported to be stable for four months at refrigerated or room temperature in amber glass bottles.3
  2. A 0.5mg per mL oral liquid prepared from tablets or injection in a base of syrup, sodium benzoate 0.1% and citric acid was reported to be stable for at least six months at 25°C in amber glass bottles.4
Due to the lack of microbial testing and evaluation of stabilty under in use conditions, a maximum expiry date of 30 days is recommended for these formulations.

REFERENCES
  1. Ahmed GH, Stewart PJ, Tucker IG.  The stability of extemporaneous paediatric formulations of propranolol hydrochloride.  Aust J Hosp Pharm 1988; 18 (5): 312-8.
  2. Ahmed GH, Stewart PJ, Tucker IG.  Extraction of propranolol hydrochloride from crushed tablets.
    Aust J Hosp Pharm 1987; 17 (2): 95-8.
  3. Henry DW, Repta AJ, Smith FM, White SJ.  Stability of propranolol hydrochoride suspension compounded from tablets.  Am J Hosp Pharm 1986; 43: 1492-5.
  4. Gupta VD, Stewart KR.  Stability of propranolol hydrochloride suspension and solution compounded from injection or tablets.  Am J Hosp Pharm 1987; 44: 360-1.

 
Formulation in Pharmacy Practice
2nd Edition