PHARMACOKINETICS
Pregabalin
Absorption: absorbed from the intestines by an active transport process mediated via the large neutral amino acid transporter 1 (LAT1, SLC7A5), a transporter for amino acids such as L-leucine and L-phenylalanine.
Distribution: crosses the blood–brain barrier and enters the central nervous system.
Metabolism: undergoes little or no metabolism
Elimination: eliminated renally in the urine, mainly in its unchanged form.
Half life: 6.3 hours.
Renal clearance: 73 mL/minute

Methylcobalamin
Absorption: absorbed irregularly from the distal small intestine. Distribution: distributed into the liver, bone marrow, and other tissues, including the placenta.
Half life: approximately 6 days
Metabolism: cyanocobalamin and hydroxocobalamin are metabolized in the liver.
Route of elimination: This drug is partially excreted in the urine


PHARMACODYNAMIC
Pregabalin binds with high affinity to the alpha 2-delta site (an auxiliary subunit of voltage gated calcium channels) in central nervous system tissues thereby reduces calcium influx at the nerve terminals which inhibits the release of excitatory neurotransmitters such as glutamate and Ach which finally modulates nerve impulses involved in the transmission of pain.
Methylcobalamin acts to repair damaged nerve tissue in nerve disorder involved in erythroblast maturation

Seizure
Neuropathic pain
Fibromyalgia
Restless leg syndrome
Generalized anxiety disorder
Peripheral neuropathy
Megaloblastic anemia

DOSAGES
The recommended oral dose is 1 capsule b.i.d. Patient previously on gabapentin should have a wash-out period of 1 week prior to initiation of pregabalin.

Headache, dizziness, sleepiness, confusion, trouble with memory, poor coordination, dry mouth, problem with vision, weight gain.
itching, swelling, nervousness, anxiousness, involuntary or uncontrollable movements, CHF.

It should not be given in patients with suspected vitamin B12 deficiency without first conforming diagnosis.
Monitor blood regularly. Dose ˃10mcg daily may produce hematological response in patients with folate deficiency.
Leber’s disease
Tobacco amblyopia