Bumetanide enhances phenobarbital efficacy in a neonatal seizure model

Ann Neurol. 2008 Feb;63(2):222-35. doi: 10.1002/ana.21229.


Objectives: High levels of expression of the Na+-K+-2Cl- (NKCC1) cotransporter in immature neurons cause the accumulation of intracellular chloride and, therefore, a depolarized Cl- equilibrium potential (E(Cl)). This results in the outward flux of Cl- through GABA(A) channels, the opposite direction compared with mature neurons, in which GABA(A) receptor activation is inhibitory because Cl- flows into the cell. This outward flow of Cl- in neonatal neurons is excitatory and contributes to a greater seizure propensity and poor electroencephalographic response to GABAergic anticonvulsants such as phenobarbital and benzodiazepines. Blocking the NKCC1 transporter with bumetanide prevents outward Cl- flux and causes a more negative GABA equilibrium potential (E(GABA)) in immature neurons. We therefore tested whether bumetanide enhances the anticonvulsant action of phenobarbital in the neonatal brain

Methods: Recurrent seizures were induced in the intact hippocampal preparation in vitro by continuous 5-hour exposure to low-Mg2+ solution. The anticonvulsant efficacy of phenobarbital, bumetanide, and the combination of these drugs was studied

Results: Phenobarbital failed to abolish or depress recurrent seizures in 70% of hippocampi. In contrast, phenobarbital in combination with bumetanide abolished seizures in 70% of hippocampi and significantly reduced the frequency, duration, and power of seizures in the remaining 30%

Interpretation: Thus, alteration of Cl- transport by bumetanide enables the anticonvulsant action of phenobarbital in immature brain. This is a mechanistic demonstration of rational anticonvulsant polypharmacy. The combination of these agents may comprise an effective therapy for early-life seizures.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Anticonvulsants / pharmacology
  • Anticonvulsants / therapeutic use
  • Bumetanide / pharmacology*
  • Bumetanide / therapeutic use
  • Chloride Channels / drug effects
  • Chloride Channels / metabolism
  • Chlorides / metabolism
  • Drug Synergism
  • Drug Therapy, Combination
  • Epilepsy, Benign Neonatal / drug therapy*
  • Epilepsy, Benign Neonatal / physiopathology
  • Hippocampus / drug effects*
  • Hippocampus / growth & development
  • Hippocampus / physiopathology
  • Ion Transport / drug effects
  • Ion Transport / physiology
  • Magnesium Deficiency / complications
  • Magnesium Deficiency / physiopathology
  • Male
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Models, Biological
  • Neural Inhibition / drug effects
  • Neural Inhibition / physiology
  • Organ Culture Techniques
  • Patch-Clamp Techniques
  • Phenobarbital / pharmacology*
  • Phenobarbital / therapeutic use
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, GABA-A / drug effects
  • Receptors, GABA-A / metabolism
  • Seizures / drug therapy*
  • Seizures / physiopathology
  • Sodium Potassium Chloride Symporter Inhibitors / pharmacology
  • Sodium Potassium Chloride Symporter Inhibitors / therapeutic use
  • Sodium-Potassium-Chloride Symporters / drug effects
  • Sodium-Potassium-Chloride Symporters / metabolism
  • Solute Carrier Family 12, Member 2


  • Anticonvulsants
  • Chloride Channels
  • Chlorides
  • Receptors, GABA-A
  • Slc12a2 protein, rat
  • Sodium Potassium Chloride Symporter Inhibitors
  • Sodium-Potassium-Chloride Symporters
  • Solute Carrier Family 12, Member 2
  • Bumetanide
  • Phenobarbital