Pharmacology Flashcards
Which is the only antidepressant recommended in <18y? why?
Fluoxetine
Because of increase in suicidal thoughts in the others
What are 4 classes of antidepressants?
SSRIs
SNRIs
MAOIs
TCAs
Which of the following is not an SSRI:
citalopram, duloxetine, sertraline, paroxetine
duloxetine is an SNRI
What does SNRI stand for
serotonin and noradrenaline reuptake inhibitor
SEs SSRI
GI bleed, sexual dysfunction, hyponatraemia, increase in suicidal ideation, QT prolongation
Any drug that increases the availability of serotonin can cause____?
serotonin syndrome
Symptoms of serotonin syndrome
confusion
delirium
shivering
sweating
BP changes
myoclonus
In which situations is serotonin syndrome likely to occur?
When initiating an antidepressant, increasing the dose, overdose, adding another AD or switching AD without allowing ‘washout period’ of the last one
How can you reduce the risk of GI bleed in SSRI
if elderly taking NSAID/aspirin give PPI
Which two SSRIs would be good for patients on a lot of medication?
Citalopram and sertraline have fewest interactions
How should a patient starting an antidepressant be monitored?
Review every 1-2w at the start (1w if <30 or suicide risk). Wait at least 4w before deciding it isn’t working. If partial response, keep waiting for another 2-4 more weeks. See them every 2-4w in the first 3m.
If <30 or suicide risk- see frequently until the risk is no longer clinically significant.
Name two SNRIs
venlafaxine, duloxetine
Which SNRI has different side effects to SSRIs?
Venlafaxine
What extra SEs does venlafaxine have?
BP changes, cardiotoxic in overdose
How long should you remain on an antidepressant for?
about 6m after symptom resolution
How are antidepressants metabolised
hepatic
Can any antidepressants cause withdrawal symptoms?
Yes
How should you come off antidepressants?
Taper over 2-4w
What is the action of Mirtazapine?
Blocks presynaptic alpha 2 receptors which normally inhibit neurotransmitters via negative feedback. This increases monoamine output
Side effects of mirtazipine
Dry mouth, drowsiness, wt gain
Dothiepin, imipramine and lofepramine are what type of antidepressant?
TCA
What type of antidepressant has the highest risk of overdose?
TCAs except lofepramine
Mechanism of TCAs
Block monoamine reuptake (each to different extents)
SEs TCAs
Anticholinergic, antiadrenergic, cardiac arrhythmias, seizures
hypotension, tachycardia, QTc prolongation
Which TCA has fewer side effects
Lofepramine, but rarely it causes hepatic toxicity
TCAs can be split into what two groups?
Sedating and non-sedating
Name some sedating TCA
amitriptyline, clomipramine, dosulepin, doxepin, mianserin, trazodone, trimipramine
Name some less sedating TCAs
Imipramine, lofepramine, nortriptyline.
Mechanism of MAOIs?
Inhibit breakdown of serotonin, and, to a lesser extent, noradrenaline.
Name two MAOIs
phenelzine, tranylcypromine
SEs MAOIs
Anticholinergic, antiadrenergic, tyramine reaction
Hypertensive crisis
What is a tyramine reaction (SE of MAOI)
HTN and throbbing headache if eat food with lots of tyramine- cheese and red wine. Occasionally fatal.
Treatment with _______ is associated with a higher risk of withdrawal effects compared with other antidepressants
Venlafaxine
What is the antidepressant general progression of treatment?
- SSRI
- Up dose
- Switch to different SSRI or alternate antidepressant
- Augment with antipsychotic/lithium etc
- Combination therapy: Venlafaxine & Mirtazapine, or Olanzapine & Fluoxetine
Antipsychotics are split into which two categories?
Typical and atypical
Are typical or atypical antipsychotics first line?
Atypical
Benefit of atypical antipsychotics?
Fewer SEs and may be slightly better at treating negative Sx schizophrenia
Which is the most effective antipsychotic? But what are its negatives?
Clozapine
Significant SEs- agranulocytosis- requires regular monitoring (weekly for 18w, then fortnightly for 1y then monthly).
When do you prescribe clozapine?
when two antipsychotics have failed
Mechanism of action antipsychotics?
Reduce dopamine transmission (D2/D3)
Atypicals- antagonise 5HT2a receptors
Typicals- anticholingergic, antiadrenergic and antihistaminergic.
Unknown why these treat psychosis
May involve ventral striatum
antipsychotics route?
Normally oral, can be IM short acting, occasionally IV.
Some (flupenthixol, fluphenazine and risperidone) can be depot injections every 1-4w which improves adherence.
Would you use antipsychotics for behavioural disturbance in elderly?
No, risk stroke and reduce glycaemic control. Only one you’d use is risperidone short term.
Indications for antipsychotics?
Schizo
Mania
Psycotic depression
Violent/agitated behaviour (haloperidol usually)
Tourette’s in lower doses
SEs typical antipsychotics
Antidopaminergic:
Movement: parkinsonism, akathisia, tardive dyskinesia, acute dystonic reactions (torticollis, increased tone, oculogyric crisis)
AND
Hyperprolactinaemia: galactorrhoea, breast cancer, amenorrhoea, sexual dysfunction
What is an oculogyric crisis?
Keep looking up involuntarily
What types of typical antipsychotics have slightly different SEs?
Phenothiazines- blood dyscrasias, retinal pigmentation, photosensitivity, cholestatic jaundice
What are the SEs of atypical antipsychotics?
Metabolic- wt gain, T2DM, dyslipidaemia
Which atypical antipsychotic has different profile of SEs?
Clozapine:
Nocturnal enuresis, constipation, salivation, BP changes, fever, nausea, seizures, agranulocytosis
What are the side effects of all antipsychotics?
C-CHANS
Cardiac (QT prolongation, arrhyth, 2x risk sudden cardiac death)
Anti-Cholinergic (dry mouth, urinary retention, constipation, confusion)
Anti-Histaminergic (sedation)
Anti-Adrenergic (postural hypotension)
Neuroleptic malignant syndrome
Change Seizure threshold
What is neuroleptic malignant syndrome?
Increased serum CK, hyperpyrexia, increased muscle tone, confusion, autonomic instability
How long should antipsychotics be continued?
1-2y after first episode, but 98% relapse after 2y so often continue for 5y. Many are non-adherent anyway
What advice should you give to patients if they decide to stop their antipsychotic?
Taper it over at least 3w as stopping suddenly doubles the risk of relapse
What monitoring should be done when starting antipsychotics? And how frequently after starting?
Prior and yearly:
- ECG
- BMI and waist circ
- Bloods: FBC, U&E, lipid profile, HbA1c, glucose, LFTs, prolactin
Why can’t clozapine and carbemazepine be used together?
Both risk agranulocytosis
What is the risk with antipsychotics and metaclopramide?
Extra pyramidal SEs
Risk with (IV) erythromycin & quetiapine?
QT prolongation
What is the main mood stabiliser?
Lithium
Indications for lithium?
Prophylaxis in recurrent uni/bipolar affective disorder
Acutely in mania
Augmentation of ADs in resistant depression
Schizoaffective illness
Control aggression
Mechanism of lithium
Unclear
Interacts with all body systems that involve sodium, potassium, calcium and magnesium
probably affects neurotransmitters (serotonin, dopamine, noradrenaline, acetylcholine)
Interferes with cAMP linked receptors- action on kidney and thyroid
Route of lithium
Oral
Excretion of lithium
Renal