Pharmacology Flashcards
What type of drug can effectively diffuse across the BBB?
Lipophilic/hydrophobic
Give an example of a lipophilic drug that is used for anxiety
Propranolol - more lipophilic than other beta blockers
State the uses of antidepressant drugs
- moderate/severe depression
- dysthymia
- generalised anxiety disorder
- panic/OCD/PTSD
- bulimia nervosa
- neuropathic pain
- premenstrual dysphoric disorder
Name three classes of antidepressants
Monoamine oxidase inhibitor
Monoamine reuptake inhibitor
Atypical drugs (post synaptic)
Name three monoamines
- dopamine
- noradrenaline
- 5 HT/serotonin
Where is serotonin produced?
Raphe nucleus
Where are most serotonin neurons located?
Rostral nucleus but has multiple cortical projections to areas involving mood, sleep, feeding, behaviour and sensory perception
Other than serotonin production what is the raphe nucleus also involved in?
Analgesia
Where is noradrenaline produced?
Locus coeruleus with projections to areas of arousal and emotion
What is the function of MAO?
Converts monoamines into metabolites
How do monoamine oxidase inhibitors work?
Prevent the conversion of neurotransmitter to metabolite
Give two examples of MAOi
Phenelzine (irreversible)
Moclobemide (reversible)
What are the side effects of MAOi?
Cheese reaction Decreased metabolism of other drugs Insomnia Postural hypotension Peripheral oedema
Describe the cheese reaction
Hypertensive crisis, inhibition of MAO in the gut prevents breakdown of dietary tyramine - tyramine causes vasoconstriction and malignant hypertension
How do tricyclic antidepressants work?
Block uptake of amines by competition of nerve terminals - non-specific inhibition of noradrenaline and 5HT uptake
Give examples of tricyclic antidepressants
Imipramine
Dosulepin
Amitriptyline
Lofepramine
What are the side effects of tricyclic antidepressants?
Anticholinergic syndrome, sedation, weight gain, constipation, cardiotoxic in overdose and cardiovascular effects of increased noradrenaline
How to SSRIs work?
Inhibit re-uptake of 5HT from the synaptic cleft
Give examples of SSRIs
Fluoxetine, citalopram, sertraline
What are the side effects of SSRIs?
Nausea, headache, worsened anxiety, <25 year olds risk of increased self harm and suicidal ideation, sweating/vivid dreams, sexual dysfunction, hyponatraemia (elderly)
How do monoamine reuptake inhibitors work?
Block the reuptake of monoamines - noradrenaline and 5HT into presynaptic terminals
Give examples of monoamine reuptake inhibitors
Duloxetine and Venlafaxine
What are the side effects of monoamine reuptake inhibitors?
Similar to SSRI but lack of major receptor blocking actions so a more limited range of side effect than tricyclics
Name two types of atypical antidepressant
- Mirtazapine (mixed receptor effects)
- Dopamine uptake inhibitor (Bupropion)
When can mirtazapine be used?
With SSRI to block serotenergic side effects
What are the side effects of mirtazapine
Weight gain and sedation
How is lithium given to a patient?
As a salt usually lithium carbonate
How does lithium work?
- blocks phosphatidylinostol pathway
- inhibits glycogen synthase kinase 3beta
- modulates NO signalling
What is the issue with lithium?
Requires close monitoring as it has a narrow therapeutic index - 12 hour post dose bloods (0.4-1mmol/l target)
What are the side effects of lithium?
Dry mouth, diabetes insipidus, polydipsia/uria, hypothyroid, reduced renal function, weight gain
Why must dehydration be avoided in patients who take lithium?
Renal tubules cannot differentiate between sodium and lithium ions, in dehydration more sodium is resorbed so more lithium is resorbed
Describe the toxic effects of lithium
- Vomiting
- Ataxia/tremor
- Drowsiness
- Convulsion
- Coma
- Diarrhoea
What anticonvulsants can be used long term in bipolar?
Valproic acid, lamotrigine, carbamazepine - sodium channel blockers
When must valproic acid not be used?
Pregnancy - neural tube defect
What is a rare side effect of lamotrigine?
Steven Johnson Syndrome
What are the side effects of valproate and carbamazepine?
Ataxia, drowsiness, induction of liver enzymes
Which antipsychotics can be used in bipolar?
Quetiapine, Aripiprazole, Olanzapine, lurasidone - act as dopamine and 5HT antagonists
Which antipsychotics can be used in bipolar?
Quetiapine, Aripiprazole, Olanzapine, lurasidone, risperidone - act as dopamine and 5HT antagonists