Serotonin and Dopamine

Question 1

Serotonin Synthesis

Answer 1

L-Tryptophan → 5-HTP→ Serotonin→5-HIAA (excreted)

metabolized by MAO

Question 2

Dopamine

Answer 2

DA and adrenergic receptor agonist

Shock, cardiac decompensation

Hypotension (low dose)

Question 3

Buspirone

Answer 3

5-HT_1A Partial Agonist

Indications: Gerneralized anxiety disorder. off label SSRI for major depression.

MOA: not known but likely due to activation of post-synaptic recptors in cortical regions, partial agonist at 5-HT_1A receptor.

Side effects: can increase anxiety during initial treatment, drowsiness (but less than bezodiazapines)

Question 4

Sumatriptan

Answer 4

5-HT_D1

MOA: inhibition of inflammatory mediator release from sensory neurons that innervate vasculature, cerebrovasoconstriction. Coupled to same mechanism as 1A receptor.

Indication: Prophylactic for migraine

SE: Coronary vasoconstriction via 5-HT_D1 receptor

Contraindication: pts with coronary artery disease.

Question 5

Fluoxitine, Sertraline

Answer 5

SSRI

Indications: depression, PTSD, OCD, anxiety, panic disorder, PTSD, social phobia

MOA: increases 5-HT post synaptic receptor activation.Increased activations of 5HT_1A in cortex.

Takes 2-4 weeks for full effect due to autoreceptor activation.

SE: sexual dysfunction, insomnia

Contraindiacations: MAO inhibitor. can cause serotonin syndrome (hyperthermia, mental status changes, seizures)

Question 6

Trazadone

Answer 6

Seratonin antagonist reuptake inhibitor (SARI)

MOA: 5-HT_2A/2C antagonist + SSRI hypnotic, SSRI, blocks side effects associated with SSRIs

Indication: anxiety, depression (incombination with SSRI)

SE: suicidality in young adults at initiation of treatment.

Contraindications: MAO inhibitors

Question 7

Respiradone

Answer 7

2nd genertion anti-psychotic

MOA: 5-HT_2A and D_2/3 antagonist. Supresses DA release in meoslimbic pathway, but increases DA relelase in mesocortical pathway.

Indication: Schizophrenia with psychosis. depression

SE: weight gain, anxiety, akithesia (restlesness). can get psychosis with abrupt discontinuation.

Question 8

Ondansetron

Answer 8

5-HT₃ receptor agonist

Indication: chemotherapy enduced emesis.

MOA: blocks 5-HT₃ receptor.

SE: well tolerated

Question 9

Mosapride, Cisapride

Answer 9

5-HT₄ receptor agonist

MOA: 5-HT₄ induced stimulation of Ach release in the myenteric plexus

Indication: gastroparesis

SE: arrhythmia (long QT syndrome)

Question 10

Schizophrenia

Answer 10

lack of DA in mesocortical region

Question 11

Psychosis

Answer 11

hyperactive DA in the mesolimbic cortex

Question 12

Parkinsons

Answer 12

lack of DA in negrostriatal region of brain

Question 13

Haloperidol

Answer 13

MOA: D₂ antagonist

Indications: Acute psychosis. long term depot for poorly compliant schizophrenic patients.

SE: extrapyramidal motor disturbances

Question 14

methylphenidate

Answer 14

MOA: increased DA release in frontal cortex.

Indication: ADHD

SE: tachycardia

Contraindication: tricyclic anti-depressant, arrhythmia, hypertension.

Question 15

Metaclopramide

Answer 15

D₂ receptor antagonist, block nausea

Indication: chemotherapy induced/post-op nausea and vomiting. gastric paresis

MOA: D₂ antagonist, has 5-HT₄ agonist properties.

SE: akathisia, focal dystonia

Contraindications: long term rx (3months, can cause tardive dyskinesia)

Question 16

L-DOPA

Answer 16

Dopamine precursor

Parkinon’s disease

SE: arrhythmia, dyskinesis

Question 17

Bromocriptine

Answer 17

D2 agonist

Parkinson’s disease

SE: cardiovalvular fibrosis

Question 18

Carbidopa

Answer 18

Aromatic acid decarboxylase inhibitor

Parkinson’s disease

SE: same as L-DOPA since it increases DA. arrhythmia, dyskinesis

Question 19

Selegiline

Answer 19

MAO-B inhibitor

Parkinson’s Disease

Dyskinesia

Question 20

Talcapone

Answer 20

COMT inhibitor

Parkinson’s disease Dyskinesia