Formulation in Pharmacy Practice   2nd Edition

NIFEDIPINE
 
Nifedipine is practically insoluble in water and is extremely light sensitive.  Preparation of a mixture from tablets or by dilution of the contents of capsules is not recommended.

Sublingual absorption of nifedipine is incomplete and unreliable, and much of the dose is actually swallowed and absorbed in the normal way.1,2  The use of sublingual nifedipine for rapid control of hypertension is no longer generally recommended and alternative agents are available.

The removal of nifedipine liquid from capsules with a needle and syringe can lead to very erratic and variable dose administration.3  It is impossible to withdraw all the liquid.4  If the concentration of nifedipine in the capsule is known, it is easier to withdraw the required volume from 2 - 3 capsules.

The successful use of rectal nifedipine in young children with acute hypertension has been described.5  The total amount of drug and the volume in the capsule were determined (obtained from manufacturer's data), and the extra contents were removed with a syringe leaving the required dose in the capsule.  A second hole was made in the capsule, which was then given rectally.

Helin et al6 investigated the preparation of nifedipine powders manufactured in a dimly lit room and then sealed in wax paper.  Tablets were crushed and diluted with lactose (1mg per 500mg) and the powder then added to flavoured food or liquid as required.   Nifedipine started to degrade as soon as the sealed papers were opened (losing up to 20% within 3 hours).

REFERENCES
  1. McAllister RG Jr.  Kinetics and dynamics of nifedipine after oral and sublingual doses.
    Am J Med 1986; 81 (suppl. 6A): 2-5.
  2. van Harten J., Burgraaf K., Danholf M., van Brummelen P., Breimer D.D.  Negligible sublingual absorption of nifedipine.  Lancet 1987; 2: 1363-5.
  3. Woods DJ, Fowler S.  Nifedipine for hypertensive emergencies.  JAMA 1997; 277 (10): 790.
  4. Domaratzki J., Campbell S.  Nifedipine administration in the critically ill.  Can J Hosp Pharm 1988: 41 (1): 34-5.
  5. Uchiyama M., Ogawa I.  Rectal nifedipine in acute severe hypertension in young children (letter).
    Arch Dis Child 1989: 64 (4): 632.
  6. Helin M.M., Kontra K.M., Naaranlhti T.J., and Wallenius K.J.  Content uniformity and stability of nifedipine in extemporaneously compounded oral powders.  Am J Health Syst Pharm 1998; 55: 1299-301.

 
Formulation in Pharmacy Practice
2nd Edition