Sun 44, a prodrug of Gabapentin, is being developed as a gabapentin with improved pharmacokinetics. Gabapentin, an analogue of the brain neurotransmitter GABA, is prescribed in the treatment of epilepsy, as also for the treatment of neuropathic pain, restless leg syndrome, mood disorders.
Gabapentin has a non-linear dose dependant bioavailability, as the dose is increased, the percentage of absorption decreases. This is because the transport mechanism in the intestine gets saturated at a higher dose level. Also, the expression of the transporter that links with the molecule and carries it across the gastrointestinal tract tissues, may vary from patient to patient. The molecule is also excreted relatively rapidly, hence there is a great deal of variation in patient responses to the drug.
Sun 44 has been designed to address this bioavailability issue. Once absorbed, Sun 44 is converted to gabapentin. In animal studies, gabapentin shows good efficacy and rapid absorbtion.
Also, Sun 44 does not raise any additional safety concerns on account of its molecule structure. Organ toxicities related to acetaldehyde, such as liver, brain, and cardiac toxicities have not been observed.
IND has been approved by the regulatory authority in India. Phase I trials are now to be initiated.