Neurotransmitter Receptor Hypothesis of Antidepressant Action Decreased state due to up-regulation of receptors Stahl S M, Essential Psychopharmacology (2000)
Neurotransmitter Receptor Hypothesis of Antidepressant Action Antidepressant blocks the reuptake pump, causing more NT to be in the synapse Increase in NT causes receptors to down-regulate Stahl S M, Essential Psychopharmacology (2000)
Affect only the reuptake pumps responsible for 5HT
Because of this, SSRIs lack some of the side effects of the more general drugs
History Of SSRI’s
SSRI’s were introduced in 1987
The first was Fluoxetine (Prozac:Eli Lilly & Company) FDA approved 1987
Sertraline (Zoloft; Pfizer, Inc) FDA approved 1991
Paroxetine (Paxil; GlaxoSmithKline) FDA approved 1992
Citalopram (Celexa; Forest Pharmaceuticals) FDA approved 2000
Escitalopram (Lexapro; Forest Pharmaceuticals) FDA approved 2002
Also known as 5-HT, derived from tryptophan (amino acid)
It is widely distributed in the animal and vegetable kingdoms
In mammals it is found in ---
gastrointestinal enterochromaffin cells
(McGraw-Hill Encyclopedia of Science and Technology, 2005)
Serotonin is concentrated in certain areas of the brain---
Other indications of SSRI
Anxiety disorders :
SNRIs were developed more recently than SSRIs
Their efficacy as well as their tolerability appears to be somewhat better than the TCA’s.
venlafaxine is approximately 3- to 5-fold more potent at inhibiting serotonin than noradrenaline reuptake
It has low affinity for cholinergic, histamine H1 and adrenergic receptors.
Venlafaxine is the first and most commonly used SNRI.