Pharmacology Flashcards
What are the pharmalogical effects of benzodiazepines?
- reduce anxiety and aggression
- hypnosis/sedation
- muscle relaxation
- anticonvulsant effect
- anterograde amnesia
What are the clinical uses of benzodiazepines?
- Acute treatment of extreme anxiety
- Hypnosis
- Alcohol withdrawal
- Mania
- Delirium
- Rapid tranquillisation
- Premedication before surgery or during minor procedures
- Status epilepticus
How do antidepressants work?
Increase monoamine neurotransmitters (5-HT/serotonin, dopamine and noradrenaline) in the synaptic cleft
What are the three main types of antidepressant?
SSRI
Tricyclics
MAOIs
What are examples of tricyclic antidepressant?
Amitriptilline and clomiprimine
How do tricyclic antidepressants work?
Act on the presynaptic terminal to block the re-uptake of noradrenaline and serotonin, increasing avaliability of these neurotransmitters
When are tricyclic antidepressants used?
Depression
Anxiety disorders
Chronic pain
Insomnia
Migraines
What are the side effects associated with tricyclic antidepressants?
Muscarinic: dry mouth, blurred vision, urinary retention, constipation
Alpha-adrenergic: postural hypotension, sexual dysfunction
Cardiotoxic: long QT, ST segment elevation, arrythmias
Antihistaminergic: weight gain, sedation
What are some of the contraindications for TCAs?
Recent MI
Arrythmias
Heart block
Liver disease
Mania
What are some examples of SSRIs?
Fluoxetine
Sertraline
Citalopram
Paroxetine
What is the mode of action of SSRIs?
Presynaptic blockade of 5-HT reuptake
When are SSRIs used?
Depression
Panic disorder
Social anxiety disorder
Stroke recovery
OCD
Chornic pain
Premature ejaculation
Bulimia (fluoxetine)
What are the first line antidepressants?
SSRIs
Which antidepressant is often used in bulimia nervosa?
Fluoxetine
What are the side effects associated with SSRIs?
GI: nausea, vomiting, diarrheoa
Initial rebound anxiety
Increased appetite
Weight changes
Sexual dysfunction
Insomnia
Hyponatremia
What is the main contraindication for SSRI use?
Mania
What is serotonin syndrome?
A rare but potentially fatal consequence of excess serotonin on the CNS
How does serotonin syndrome present?
Altered mental state
Agitation
Tremor
Shivering
Diarrheoa
Hyperreflexia
Rigidity
Myoclonus
Ataxia
Hyperthermia
What are the causes of serotonin syndrome?
Medication:
SSRIs
Amphetamines
Opiods
5-HT antagonists
Lithium
What investigations should be done if serotonin syndrome suspected?
Bloods
ECG
Drug screen
What are some examples of MAOIs?
Phenelzine
Tranylcypromine
What is the mode of action of MAOIs?
Non-selective irreversible inhibition of monoamine oxidase A and B, which act to break down monoamine neurotransmitters
Why is use of MAOIs avoided?
Serious risk of drug and food interactions causing tyramine crisis
What is tyramine crisis?
Tyramine is broken down by MAO-A, which is inhibited by use of MAOIs in depression
Increased levels of tyramine in the blood can cause a hypertensive crisis which can result in strokes and MIs
What foods should be avoided in use with MAOIs?
Cheese, especially mature cheeses
Wines and beer
Smoked fish
Chicken liver
Which drugs should be avoided in use of MAOIs?
Anaesthetics
Certain components of cough medicine
Cocaine
What are the common side effects of MAOIs?
Weight gain
Dry mouth
Constipation
Headache
Low libido
Drowsiness
Insomnia
Seizures
What are the contraindications of MAOIs?
Cerebrovascular disease
Severe liver disease
Mania
What are the three main mood stabilisers?
Litium
Sodium valproate
Carbamazipine
How long does it take for antidepressants to begin to work?
2-3 weeks
What is the gold standard treatment for bipolar disorder?
Lithium
When is lithium used clinically?
Acute mania
Prophylaxis in bipolar disorder
Treatment resistant depression
Adjunct to antipsychotics
What are some of the side effects associated with lithium?
Thirst
Polyuria
Weight gain
Oedema
Fine tremor
Skin problems
Concentration and memory problems
Hypothyroidism
What drugs can cause increased lithium levels in the body?
NSAIDs
ACE inhibitors
Diuretics
What are the symptoms of lithium toxicity?
Nausea
Vomiting
Course tremor
Ataxia
Muscle weakness
Nystagmus
Dysarthria
Drowsiness
Very toxic levels - confusion, seizures, coma
When do lithium levels need monitored?
Weekly until theraputic level has been stable for 4 weeks
Following this, lithium levels every 3 months
Renal function and TFTs every 6 months
When are antipsychotic drugs used clinically?
Psychotic disorders: schizophrenia, schizoaffective disorder, delusional disorder
Depression/mania with psychotic features
Delirium
How do antipsychotic drugs work?
Blocking D2 dopamine receptors in the mesolimbic dopamine pathways
Generally, how do typical antipsychotic drugs differ in their mechanism of action from atypical antipsychotic drugs?
Typical: block all D2 receptors
Atypical: less affinity for D2 receptors but also block 5-HT2a receptors
Which causes more extrapyramidal side effects, typical or atypical antipsychotics?
Typical, as they block all D2 dopamine receptors
What are examples of typical antipsychotics?
Haloperidol
Flupentixol
Sulpiride
What are examples of atypical antipsychotics?
Clozapine
Olanzapine
Rispiridone
Quetapine
Amisulpride
What are some of the extrapyramidal side effects associated with antipsychotic drugs?
Parkinsonian symptoms: muscle rigidity, bradykinesia, resting tremor
Acute dystonia - involuntary sustained muscle contraction e.g. clenched jaw, eyes rolling up
Akathisia - subjective feeling of restlessness
Tardive dyskinesia - rhytmic involuntary movements e.g. chewing, protruding darting movements of the tongue
Other than extrapyramidal side effects, what other side effects are associated with antipsychotic drugs?
Anticholinergic: dry mouth, contsiptaion, urinary retention, blurred vision
Alpha-adrenergic receptor blockade: postural hypotension
Histaminergic receptor blockade: sedation, weight gain
Cardiac effects: long QT syndrome, arrythmias
Hyperprolactinaemia
What is neuroleptic malignant syndrome?
A life-threatening neurological disorder most often caused by an adverse reaction to neuroleptic or antipsychotic drugs
When does neuroleptic malignant syndrome most frequently occur?
4-11 days after starting antipsychotic treatment or after a change in dose
How does neuroleptic malignant syndrome present?
Motor signs: severe muscle rigidity
Mental signs: fluxuation in levels of consciousness
Autonomic disturbance: sweating, hyperthermia, unstable BP, rapid pulse
What would blood tests show in neuroleptic malignant syndrome?
Abnormal LFTs
Raised creatine kinase levels
How is neuroleptic malignant syndrome treated?
Immediately stop antipsychotics
A&E admittance
Which antipsychotic tends to cause agranulocytosis?
Clozapine
Which antipsychotic drugs tends to cause weight gain and increased prolactin?
Rispiridone
Which antipsychotic drug has a particularly high risk of causing weight gain, diabetes and sedation?
Olanzapine
What are some examples of benzodiazepines?
Lorazepam
Temazepam
Diazepam
Chlordiazepoxide
Why are lorazepam and tempazepam known as hypnotics?
They are short acting
Why are diazepam and chlordiazepoxide known as anxiolytics?
They have long half lives
What is the main action of benzodiazepines?
They potentiate the action of GABA which is the main inhibitory neurotransmitter in the brain
How can benzodiazepines be used clinically?
Used in acute anxiety for rapid relief of symptoms
Insomnia
Siezures
Anaesthetic
Alcohol withdrawl
Tranqulisation in psychosis
Mania
Can be used as:
- hypnotics
- anxiolytics
- anticonvulsants
- muscle relaxants
How are benzodiazepines used in anxiety?
For rapid relief of symptoms
Start benzodiazepines and SSRIs at the same time to combat rebound SSRI anxiety
Remove benzodiazepines - usually not used for more than 4 weeks
Why are benzodiazepines only used in the short term?
Risk of dependance and withdrawl
What are the side effects of benzodiazepines?
Drowsiness
Ataxia
Headaches
Confusion
Respiratory depression (in IV dose)
Dependence
What is the antedote for a benzodiazepine overdose?
Temazenil
Which drugs enhance the effect of benzodiazepines?
Alcohol
Opiates
Tricyclic antidepressants
Antihistamines
Which antipsychotic drug can cause a characteristic blue-grey discolouration of the skin?
Chlorpromazine
What drug is used for alcohol withdrawl in most medical units?
Chlordiazepoxide
When is use of ECT indicated?
Catatonia
Severe depression
Prolonged or severe mania
Which psychiatric drug is most likely to cause symptoms of hypothyroidism?
Lithium