Labetalol Pathway


Labetalol has two asymmetric centers and therefore, exists as a molecular complex of two diastereoisomeric pairs. Dilevalol, the R,R’ stereoisomer, makes up 25% of racemic labetalol. Labetalol HCl combines both selective, competitive, alpha-1-adrenergic blocking and nonselective, competitive, beta-adrenergic blocking activity in a single substance. In man, the ratios of alpha- to beta- blockade have been estimated to be approximately 1:3 and 1:7 following oral and intravenous (IV) administration, respectively. Beta-2-agonist activity has been demonstrated in animals with minimal beta-1-agonist (ISA) activity detected. In animals, at doses greater than those required for alpha- or beta- adrenergic blockade, a membrane stabilizing effect has been demonstrated.

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References

  1. Borchard, U. (1998). Pharmacological properties of beta-adrenoceptor blocking drugs. Journal of Clinical and Basic Cardiology, 1(1), 5-9.
  2. DiPiro, J.T., Talbert, R.L., Yee, G.C., Matzke, G.R., Wells, B.G, & Posey, M.L. (2005). Pharmacotherapy: A pathologic approach. (6 th ed) pp.207-208. New York: McGraw-Hill Medical Publishing Division.
  3. Trandate. (2009). [Electronic version]. e-CPS. Retrieved July 25, 2009.