pharmacology Flashcards
When do we used sodium valproate?
- epilepsy (anti convulsion)
2. bipolar disorder (acute disorders and prophylaxis): mood stabiliser
What is the mechanism of action of sodium valproate?
- weak inhibitor of neuronal voltage gated NA+: stabilises resting membrane potentials and reduces neuronal excitability
- GABAergic: inhibits GABA transaminase (increases GABA concentration at receptor sites)
What are the side effects of sodium valproate?
nausea, dyspepsia, weight gain, hepatic and renal impairment, dizziness, drowsiness, thrombocytopenia, hair loss
What are the problems with using valproate sodium during pregnancy?
folate antagonist properties: inhibits the DHFR protein (enzyme used to activate folic acid and before it enters folate metabolism cycle)
What is the mechanism of action of lithium?
increase GABA
When do you use Gabapentin?
- epilepsy ( anticonvulsant): usually as an add on treatment if other epileptic drugs provide inadequate control
- Neuropathic pain
- Migraine prophylaxis
- GAD
What is the mechanism of action of gabapentin?
reduction of axon excitability:
acts on voltage sensitive calcium channels (binds to alpha-2 delta subunits): prevents inflow of calcium which inhibits neurotransmitter release (glutamate, noradrenaline and substance P)
What are side effects of gabapentin?
somnolence, dizziness, ataxia, fatigue
When do you use tricyclic antidepressants?
- moderate to severe depression (when first line SSRIs are ineffective)
(2. anxiety) - neuropathic pain
What are the side effects of tricyclic antidepressants?
- antimuscarinic receptors: dry mouth & nose, constipation, urinary retention and blurred vision
- histamine and adrenergic receptors: sedation, hypotension
- arrhythmia,ECG changes
- convulsions, hallucination and mania
DON’T STOP THEM SUDDENLY
What are the mechanism of actions of tricyclic antidepressants?
- inhibits presynaptic 5-HT and NA reuptake transporters: increase synaptic neurotransmitter availability (monoamine theory of depression)
- analgesic mechanism unknown: thought to result from modulation of inhibitory systems and opioid systems in CNS
When do you use lidocaine?
- local anaesthesia
2. ventricular arrhythmias
What is the mechanism of action of lidocaine?
Blockage of fast voltage-gated NA+ channels in neuronal membrane: prevents depolarisation along axon (propagation)
What are the side effects of lidocaine?
- dizziness/drowsiness
- paraesthesia
When do you use paracetamol?
- analgesic effects in acute and chronic pain
- reduce fever: antipyretic effects
What is the mechanism of action of paracetamol?
increases pain threshold in CNS by inhibiting COX (cyclooxyrgenase)
- reduces prostaglandin PGE2 concentration in thermoregulatory region of hypothalamus
- COX 2 inhibition: reduces inflammation (weak anti-inflammatory)
What are the SE of paracetamol?
in overdose: liver failure
When do you use ibuprofen?
- analgesia (mild to moderate pain)
- anti-inflammatory
(3. antipyretic)
What is the mechanism of action of ibuprofen?
-inhibition of COX2: prevents prostaglandin formation from arachidonic acid
(COX2 is expressed in response to inflammatory stimuli–> causes pain)
What are the SE of ibuprofen?
- -> due to COX1 inhibition:
- nausea and dyspepsia
- GI ulceration/bleeding
- risk of hypertension in chronic use
- cardiovascular event
When do you use morphine?
- acute severe pain
- chronic pain
- breathlessness (in end of life care)
- acute pulmonary oedema (breathlessness and anxiety)
What is the MOA of morphine?
Activation of mu receptors (G protein-coupled receptors) in CNS
- -> reduces neuronal excitability (post-synaptic opioid receptor activation causing hyper polarisation) recent and pain transmission (activation of pre-synaptic opioid receptors: reduced intracellular cAMP C°, decreased Ca ion influx and thus inhibits release of excitatory neurotransmitters)
- -> in medulla: blunt response to hypoxia and hypercapnoea (reduces rest drive and breathlessness)
- -> reduces fight or flight activity (by reducing pain, breathlessness and associated anxiety)
(also acts on GABA neurones that modulate dopamine: by inhibition GABA you are able to increase dopamine)
What are the SE of morphine?
- respiratory depression (by reducing respiratory drive)
- euphoria and detachment/ neurological depression
- nausea and vomiting (activa° of chemoreceptors trigger zone)
- pupillary constriction (stimulation of E-W nucleus)
- constipation (increase smooth muscle tone and reduces motility)
- skin itching (histamine release)
- -> tolerance, dependence, withdrawal reaction
What is co-codamol?
codeine and paracetamol
When do you use co-codamol?
mild to moderate pain, as a second line treatment when simple analgesics are insufficient
What is the MOA of co-codamol?
- mechanism of paracetamol
- metabolised by cytochrome P450 enzymes to morphine (or morphine related metabolites)
What are the SE of co-codamol?
- at recommended dose, SE from paracetamol are rare
- codeine: nauseas, constipation and drowsiness
When do you use aspirin?
- acute coronary syndrome an acute ischemic stroke
- long term secondary prevention in cardiovascular, cerebrovascular and peripheral arterial disease
- atrial fibrillation (if warfarin and oral anticoagulants are contraindicated)
- control mild to moderate fever and pain
What is the MOA of aspirin?
Irreversible inhibition of COX to reduce production of pro-aggregators factor thromboxane from arachidonic acid, reducing platelet aggregation
What are the SE of aspirin?
- gastrointestinal irritation and ulceration
- haemorrhage
- bronchospasm
- life threatening in overdose
What type of drug is diazepam?
benzodiazepines
When do you use benzodiazepines?
- seizures (first line)
- alcohol withdrawal reactions
- severe, disabling or distressing anxiety or insomnia (short term treatment)
What inhibits benzodiazepines? how?
flumazenil
displaces diazepam from GABA receptor
What is the MOA of benzodiazepines?
- positive allosteric modulator (POM): facilitate and enhance binding of GABA to GABA-A receptor (between alpha and gamma subunits): depressant effect on synaptic transmission (hyperpolarisation)
- -> effects: sleepiness, reduces anxiety, sedation and anticonvulsant effects
What are the SE of benzodiazepines?
- dose dependent drowsiness, sedation and coma
- loss of airway reflexes (airway obstruction and death)
- dependence, withdrawal reaction
Name an SSRI?
sertraline
When do you use SSRIs?
- moderate to severe depression (first line treatment BUT only if psychological treatments fail
- panic disorders
- obsessive compulsive disorder
What is the MOA of SSRIs?
inhibit neuronal re-uptake of serotonin from the synaptic cleft: increase availability for neurotransmission
What are the SE of SSRIs?
- gastrointestinal upset, appetite and weight disturbance (loss or gain) an hypersensitivity reactions
- suicidal thoughts and behaviour
- -> sudden withdrawal may cause problems
Name an SNRI
venlaxafine
What does SSRI stand for?
selective serotonin reuptake inhibitor
What does SNRI stand for?
serotonin and norepinephrine reuptake inhibitors
When do we use SNRIs?
- second line treatment for MDD
- general anxiety disorder
What is the MOA of SNRIs?
-serotonin and noradrenaline reuptake inhibitor (from synaptic cleft)
What are the SE of SNRIs?
- gastrointestinal upset
- CNS effect (abnormal dreams, insomnia, headache, convulsion etc)
- suicidal thoughts
- -> sudden withdrawal causes big effects
What is in co-beneldopa?
- levadopa (L-DOPA)
- peripheral dopa-decarboxylase inhibitor
- -> reduces conversion to dopamine outside the brain
When do you use co-beneldopa?
parkinson’s disease
What is the MOA of co-beneldopa?
precursor of dopamine (L-DOPA) which can cross the BBB via membrane transporters and then be converted into dopamine
What are the SE of Co-beneldopa?
- nausea, drowsiness, confusion, hallucinations and hypotension
- wearing off effect
- dyskinesias (on-off effect: phases of immobility and phases of dyskinesias)
Name a MAO-B inhibitor
selegiline
what does MAO-B stand for?
monoamine oxidase type B
When are MAO-B inhibitors used?
Parkinson’s disease
When are MAO-A inhibitors used?
depression
What is the MOA of MAO-B inhibitors?
inhibition of MAO-B which metabolises dopamine and phenylethylamine, increasing available dopamine
+enhances effects of L-DOPA
What are the Se of MAO-B inhibitors?
- dizziness, nausea, fatigue
- possible hyper sexuality or similar behaviour (due to increased dopamine)
- can cause worsening of levodopa induced dyskinesia
- sometimes hallucinations
Name two second generation (atypical) antipsychotic
clozapine and risperidone
When do we use second generation (atypical) antipsychotics?
- psychomotor agitation (urgent treatment)
- schizophrenia
- bipolar disorder (in episodes of mania or hypomania)
What are the SE of second generation (atypical) antipsychotics?
- sedation
- EPSE (ie Parkinsonism)
- metabolic disturbances
- arrhythmias
- agrunolocytosis
Which nerve fibres are more sensitive to local anaesthetics?
small nerve fibre> large nerve fibres
myelinated fibres> non myelinated fibres
when using an anaesthetics, which are the order of loss of nerve functions?
pain, temperature, touch, proprioception and finally skeletal muscle tone
Why is ketamine used in surgery?
-reduces incidence of post surgical pain
What is an adjuvant?
enhancing the effectiveness of medical treatment
what are examples of adjuvants in pain management?
- gabapentin/pregabapentin
- SNRIs/ tryclic antidepressants
- alpha2agonists
what is the MOA of cannabis?
activation of presynaptic CB1 receptors (G coupled receptors) in the hypothalamus, sustantia nigra,mesolimbic pathways and association areas of the cerebral cortex
–> causes inhibition of voltage gated Ca channels: reducing transmitter release
when is propofol used?
How is given?
- hypnosis
- bolus: fast acting but short acting
What is isoflurane used? How is given?
- hypnosis
- inhalant gas
