💊أدويه الجهاز العصبي المركزي 7
#Pharmcology_of_CNS 7
#CNS
#Antidepressants
حا نواصل في اقسام ال antidepressants
الليلة حا نتكلم عن
✔️TRICYCLIC ANTIDEPRESSANTS
✔️MONOAMINE OXIDASE INHIBITORS
كمان حا نشوف
✔️TREATMENT OF MANIA AND BIPOLAR DISORDER
✔️TRICYCLIC ANTIDEPRESSANTS
🔘The TCAs block norepinephrine and serotonin reuptake into the presynaptic neuron
تم استبدالهم بال SNRI لانو ليها نفس التأثير واقل اثار جانبية والمجموعة دي بتضم التالي:
✅imipramine
✅amitriptyline
✅clomipramine
✅doxepin
✅trimipramine
✅desipramine
✅nortriptyline
✅protriptyline
✅Maprotiline
✅amoxapine
🔵Mechanism of action
🔹Inhibition of neurotransmitter reuptake
🔹Blocking of receptors:
〰TCAs also block serotonergic, α-adrenergic,histaminic, and muscarinic receptors
🔵Therapeutic uses
🔹The TCAs are effective in treating moderate to severe depression.
Some patients with panic disorder also respond to TCAs
🔹The TCAs,particularly amitriptyline, have been used to help prevent migraine
headache and treat chronic pain syndromes (for example, neuropathic pain) in a number of conditions for which the cause of pain is unclear.
🔹Low doses of TCAs, especially doxepin, can be used to treat insomnia.
🔵Pharmacokinetics
🔹TCAs are well absorbed upon oral administration.
🔹As a result of their variable first-pass metabolism in the liver, TCAs have low and inconsistent bioavailability
🔵Adverse effects
🔹Blockade of muscarinic receptors leads to blurred vision, xerostomia
(dry mouth), urinary retention, sinus tachycardia, constipation, and
aggravation of angle-closure glaucoma
🔹The TCAs also block α-adrenergic receptors, causing orthostatic hypotension, dizziness, and reflex tachycardia. Imipramine is the most likely, and nortriptyline the least likely, to cause orthostatic hypotension
🔹Weight gain is a common adverse effect of the TCAs.
🔹TCAs (like all antidepressants) should be used with caution in patients with bipolar disorder, even during their depressed state, because antidepressants may cause a switch to manic behavior.
🔹The TCAs may exacerbate certain medical conditions, such as benign
prostatic hyperplasia, epilepsy, and preexisting arrhythmias.
✔️MONOAMINE OXIDASE INHIBITORS
🔘In the neuron, MAO functions as
a “safety valve” to oxidatively deaminate and inactivate any excess neurotransmitters (for example, norepinephrine, dopamine, and serotonin) that may leak out of synaptic vesicles when the neuron is at rest.
يعني بختصار كدا بكسر الفائض البكون ما قاعد في الvesicles عشان ما يطلع ويمشي يعمل تأثيرو في ال receptors
🔘المجموعة دي بتضم الاتي
✅phenelzine
✅tranylcypromine
✅isocarboxazid
✅Selegiline
الاخير دا لو بتتذكرو لاقانا في الادوية البتستخدم في علاج ال Parkinson’s disease وهو
the only antidepressant available in a transdermal delivery system
🔵Mechanism of action
🔹Most MAOIs, such as phenelzine, form stable complexes with the
enzyme, causing irreversible inactivation. This results in increased stores of norepinephrine, serotonin, and dopamine within the neuron and subsequent diffusion of excess neurotransmitter into the
synaptic space
🔹The MAOIs,show a high incidence of drug–drug and drug–food interactions
🔵Actions
🔹Although MAO is fully inhibited after several days of treatment, the antidepressant action of the MAOIs, like that of the SSRIs, SNRIs,and TCAs, is delayed several weeks.
🔵Therapeutic uses
🔹The MAOIs are indicated for depressed patients who are unresponsive or allergic to TCAs and SSRIs or who experience strong anxiety.
🔹Because of their risk for drug–
drug and drug–food interactions, the MAOIs are considered last-line
agents in many treatment settings.
🔵Pharmacokinetics
🔹These drugs are well absorbed after oral administration.
🔹MAOIs are hepatically metabolized and excreted rapidly in urine.
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