Typical Antipsychotics

Question 1

Mode of action

Answer 1

Dopamine hypothesis- schizophrenia was thought to be caused by an overactivity of the neurotransmitter dopamine in the brain .

Question 2

What is a typical antipsychotic

Answer 2

It’s a drug that blocks dopamine receptors,binding particularly strong to D2 receptors, thereby reducing the levels of dopamine in the brain and alleviating the symptoms of schizophrenia.

Question 3

How does an antipsychotic work

Answer 3

It works by decreasing dopamine in the mesolimbic part of the brain , this reduces positive signs of schizophrenia.
They have a non selective action on all four dopamine pathways in the brain , this is the action that causes unwanted side effects.

Question 4

What are the four dopamine pathways

Answer 4

Mesolimbic ,mesocortical , nigostriatal, tuberoinfundibular

Question 5

Mesolimbic

Answer 5

Causes reduction in positive symptom

Question 6

Mesocortical

Answer 6

Can increase negative symptoms

Question 7

Nigostriatal

Answer 7

Causes extra pyramidal side effects

Question 8

Tuberoinfundibular

Answer 8

Causes prolactin side effects

Question 9

Typical antipsychotic potency

Answer 9

Typical medications bind differently to D2 receptors,those that bind more strongly to the D2 receptors are generally high potency drugs are required in smaller doses e.g halperidol.
Less strong / less potent may be required in higher doses e.g chlorpromazine

Question 10

Antipsychotic side effects

Answer 10

They contribute significantly to non- adherence with the medication.
Some side effects are dangerous and potentially life threatening.
Others are physically / socially disfiguring
Frightening
Emotionally damaging

Question 11

Categories of side effects of typical antipsychotics

Answer 11

Extrapyramidal
Antimuscarnic side effects
Prolactin side effects
Cardiovascular
Neuroleptic malignant syndrome
Miscellaneous

Question 12

Extrapyramidal side effects

Answer 12

Akinesia
Dyskinesia
Tardive dyskinesia
Dystonia
Akathesia

Question 13

Akinesia

Answer 13

Stiffness or lack of movement , causes some like effect , severe case a person may sit motionless,can be treated by lowering the dose or providing an antimuscarinic drug., drooling ,leaning forward or to one side.

Question 14

Dyskinesia

Answer 14

Abnormal movements , ranges from a fine tremor to a clear shake , pill rolling tremor of the hand , affects mainly hands,legs and arms as well as as muscles in the face , pouting of lips .

Question 15

Tardive dyskinesia

Answer 15

Late onset , a dyskinesia that can appear several months after the drug has been started ,affects 5-20% of those antipsychotics on high doses , usually effects those on high doses for a long period.

Question 16

Dystonia

Answer 16

Abnormal muscle tone which usually occurs in form of a muscle spasm , muscles in the eye,mouth and jaw tend to be affected e.g lockjaw ,oculogyric crisis ,responds to antimuscarinic medication.

Question 17

Akathesia

Answer 17

Restlessness,ranges from feeling mildly twitchy to extreme agitation ,feel like leaping out of their skin , leg swinging ,suicide risk

Question 18

Antimuscarinic

Answer 18

Dry mouth,nasal drying ,blurred vision ,constipation ,urinary retention ,difficulty in passing urine .

Question 19

Prolactin

Answer 19

Use of antipsychotic drugs can cause hyperprolactinaemia ( high prolactin levels ).

Question 20

Prolactin side effects

Answer 20

Sexual dysfunction in men,decreased bone density ,menstrual irregularities,gynecomastia,galactorrhea

Question 21

Cardio vascular side effects

Answer 21

Tachycardia
Arrhythmias
Hypotension

Question 22

Miscellaneous side effects

Answer 22

Postural hypotension, decreased libido & sexual dysfunction, confusion,drowsiness, skin problems- burns,rash,photosensitivity, thirst / compulsive drinking - affects 20% of individuals on long term antipsychotics, weight gain , metabolic syndrome - increased weight

Question 23

Neuroleptic malignant syndrome

Answer 23

Rare but life threatening,from late 90s incidence ranged from 0.2% to 3.2% of patients receiving neuroleptic malignant

Question 24

Clinical features of nms

Answer 24

Tremor,dehydration , incontinence ,sweating , increased white blood cell count