Open-label Extension to Protocol 1042-0500

An Open-label Clinical Study to Evaluate the Safety and Antiepileptic Activity of Ganaxolone in Treatment of Patients Diagnosed With Infantile Spasms.

To allow open-label extension to patients who have completed Protocol 1042-0500

Patient should have completed all scheduled clinical study visits in the double blind, controlled trial (Protocol 1042-0500) and have been deemed eligible (had a response to treatment) by the Investigator. Male or female, with a diagnosis of IS with a video EEG (vEEG) recording confirming the diagnosis.

There will be a total of 14 visits over 99(+or-1)week. A 24-hr vEEG is only required if the subject has been spasm-free for more than 24-hrs.

Inclusion Criteria:

• Have completed all scheduled clinical study visits in the previous Protocol 1042 0500 and have been deemed eligible (no SAEs thought to be drug related and had a response to treatment) by the Investigator.
• Be diagnosed with IS regardless of etiology. Diagnostic Criteria: Seizures consisting of single or repetitive short muscular contractions leading to flexion or extension. Spasms may be characterized as tonic or myoclonic contractions, may occur singly or in clusters, and typically occur bilaterally and symmetrically. The EEG pattern must be consistent with the diagnosis of IS (hypsarrhythmia, modified hypsarrhythmia, multifocal spike wave discharges, etc).
• Have a 24 hour vEEG recording confirming the diagnosis of IS.
• Have had a magnetic resonance imaging (MRI) performed to determine any possible causes of IS.
• Have been previously treated with 3 AEDs or fewer.
• Have a parent/guardian who is properly informed of the nature and potential risks and benefits of the clinical study, is willing and capable of complying with all clinical study procedures, and has given informed consent in writing prior to entering the clinical study.

Exclusion Criteria:

• Current treatment with more than 2 concomitant AEDs.
• Have an active CNS infection, demyelinating disease, degenerative neurological disease, or CNS disease deemed progressive (with the exception of tuberous sclerosis) as evaluated by brain MRI.
• Have any disease or condition (medical or surgical) at Screening that might compromise the hematologic, cardiovascular, pulmonary, renal, GI, or hepatic systems; or other conditions that might interfere with the absorption, distribution, metabolism, or excretion of the investigational product, or would place the subject at increased risk.
• Aspartate transaminase (AST), alanine transaminase (ALT), or total bilirubin greater than 4 times the upper limit of laboratory normal or any clinical laboratory value deemed clinically significant by the Investigator.
• History of recurrent status epilepticus.
• Have been exposed to any other investigational drug within 30 days prior to enrollment.