Carbamazepine blocks adenosine A1 receptors — the same receptor action as caffeine
Acutely that is pro-epileptic: A1 blockade enhances excitatory transmission onto hippocampal CA1 pyramidal cells at therapeutic concentrations, with no matching change in inhibition
Chronic dosing runs the other way — persistent upregulation of brain adenosine receptors after chronic carbamazepine (1987)
In astrocyte culture the upregulation appears only where basal A1 is low, and brings a coupling to phospholipase C that was not there before (1999)
The evidence is not uniform: oral carbamazepine had no major effect on mouse brain A1 receptors (1991), and chronic carbamazepine down-regulates A2 receptors
A net rise in A1 signaling is a proposed antimanic mechanism — a hypothesis, not a demonstrated pathway. The receptor papers make no such claim
Drugs with this mechanism (4)
Carbamazepine — Anticonvulsant/mood stabilizer and potent autoinducer; HLA-B*1502 rash risk.
Carbamazepine ER capsules — Bead-filled extended-release carbamazepine capsule that can be opened and sprinkled.
Carbamazepine ER (Equetro) — Carbamazepine ER capsule - the only carbamazepine approved for acute bipolar mania.
Carbamazepine XR — Extended-release carbamazepine for seizures and trigeminal neuralgia; potent enzyme inducer.