Drugs action and side effects Flashcards
Treatment of GAD?
CBT
SSRI/SNRI
Pregabalin; long term
Benzo (short term)
Treatment of panic disorder?
CBT
SSRI/SNRI/ TCA
Benzo (short term)
Treatment of specific phobias?
Behavioural therapy; exposure
Add CBT if necessary
SSRI/SNRI if required
Treatment of social phobia?
CBT
SSRI/SNRI
Benzo
Treatment of OCD?
CBT (including response prevention)
SSRI/ Clomipramine (TCA)
Action of benzodiazepines?
GABA-A receptor is an inhibitory ionotropic receptor
In the presence of GABA, the ion channel allows chloride ion influx
Membrane hyperpolarisation
Inhibitory postsynaptic potential
Benzodiazepines enhance the effect of GABA via allosteric modulation
What do agonists at the benzodiazepine site on the GABA-A receptor cause?
Relaxation and anticonvulsant effects
What do antagonists at the benzodiazepine site on the GABA-A receptor cause?
Anxiety
Proconvulsant
What other drugs act on the BZD site on the GABA-A receptor?
Alcohol
Barbituates
Adverse effects of BZD?
Sedation and psychomotor impairment Discontinuation/ withdrawal problems Dependency and abuse Alcohol interaction Can worsen co-morbid depression
What properties do psychiatric drugs need to have?
Lipophilic/ hydrophobic to pass through the BBB
Clinical uses of antidepressant drugs?
Moderate to severe depression Dysthymia GAS Panic disorder/ OCD/ PTSD Premenstrual dysphoric disorder Bulimia nervosa Neuropathic pain
What are examples of monoamine reuptake inhibitors?
TCAs
SSRI
NA reuptake inibitors
SNRI
Monoamine transmitters
NA
5-HT
Dopamine
Base amino acid of serotonin?
Typtophan
Base amino acid of NA?
Tyrosine
Examples of MAO inhibitors?
Phenelzine
Moclobemide
Mode of action of MAO inhibitord?
Irreversible (phenelzine) or reversible (moclobemide) inhibitors of MAO-A and B
Side effects of MAO inhibitors?
Cheese reaction/ hypertensive crisis: inhibition of MAO-A in gut preventing breakdown of dietary tyramine and multiple drugs that potentiate amine transmission (pseudoephedrine) Potentials barbiturates Insomnia Postural hypotension Peripheral oedema
Examples of TCAs?
Impiramide
Dosulepin
Amitriptyline
Lofepramine
Mode of action of TCAs
Blocks reuptake of monoamines (mainly NA and 5-HT) into the presynaptic terminas
Common side effects of TCAs?
Anticholinergic; blurred vision, dry mouth, constipation, urinary retention
Sedation
Weight gain
CV; postural hypotension, tachycardia, arrhythmias
Cardiotoxic in overdose; do NOT give post MI or in IHD
Examples of SSRIs?
Fluoxetine Citalopram Escitalopram Sertraline Paroxetine
Mode of action of SSRIs?
Selectivity inhibit reuptake of serotonin (5-HT) from the synaptic cleft
Common side effects of SSRIs?
Nausea Headache Sweating/ vivid dreams Worsened anxiety Sexual dysfunction Hyponatraemia (elderly) Transient increase in self harm and suicidal ideation in under 25 Discontinuation effects
Examples of SNRIs?
Venlafaxine
Duloxetine
Mode of action of SNRIs?
Block reuptake of monoamines NA and 5-HT into presynaptic terminals
Side effects of SNRIS?
Similar to SSRIs
Lack major receptor-blocking actions so more limited range of side effects that TCAs
What does mirtazapine act on?
Alpha 2
5-HT2
5-HT3
When is mirtazapine useful?
For weight gain and sedation; if weight loss and insomnia are issues
Example of dopamine uptake inhibitor
Buproprion
Mode of action of lithium
Blocks phosphatidylinositol pathway or inhibit glycogen synthase kinase 3-beta
When should blood levels of lithium be checked?
12 hours post dose then 1 week
Side effects of lithium at therapeutic doses?
Dry mouth/ strange taste Polydipsia and polyuria Tremor Hypothyroidism Long term reduced renal function Nephrogenic DI Wt gain
Toxic effects of lithium in overdose?
Vomiting Diarrhoea Ataxia/ coarse tremor Drowsiness Convulsions Coma
What anticonvulsants are used as mood stabilisers?
Valproic acid (mainly mania)
Lamotrigine (mainly depression)
Carbamazepine
Side effects of lamotrigine?
Stevens johnson syndrome
Side effects of valproate and carbamazepine?
Drowsiness
Ataxia
CV effects
Induces liver enzymes
Can valorpate be given in pregnancy?
NO; neural tube defects
Which antipsychotics are used as mood stabilisers?
Quetiapine
Aripiprazole
Olanzapine
Lurasidone
Mode of action of atypical antipsychotics?
D2 antagonism
5-HT antagonism
Side effects of antipsychotics?
Sedation, weight gain, metabolic syndrome
Extra-pyramidal
What extrapyramidal side effects are associated with antipsychotics?
Acute dystonic reaction; hours to days, muscle spasms. Tx with acetylcholine antagonists (procyclidine)
Akathisia (can’t stay still) - restless leg syndrome
Parkinsonism - ridigity, tremor, bradykinesia
Tardive dyskinesia - years to develop
Risperidone mode of action
Dopamine D2, 5-HT2, alpha-1 and histamine-1 receptor antagonist