Mood Stabilisers Flashcards
Name 5 Mood Stabilisers (including brand names)
- Lithium
- Sodium Valproate (Epilim)
- Semi-Sodium Valproate (Depakote)
- Carbamazepine
- Lamotrigine
What are the different Mood Stabilisers indicated for?
- Lithium; Bipolar disorder, cyclic mood disorder
- Sodium Valproates, Carbamazepine and Lamotrigine;
- anticonvulsants-treatment and management of Epilepsy
- prophylaxis or adjunct therapy of Bipolar
What is believed to be the mechanism of action for Lithium?
- Lithium is a naturally occuring salt/mineral
- Works on CNS to improve nerve cell communication-not exactly sure how?
- May alter NA transport in nerve and muscle cells, thus affecting excitability
- Changes in gene expression?
- May decrease levels of 2nd messengers (such as cAMP) inside neuron-this could allow it to selectively modulate responsitiveness of hyperactive neurons that might contribute to manic state)
- Recent theory that this occurs by activating the CRMP2 protein which is responsible for nerve cell communication.
- Despite not knowing how, it does work in 1/3 of patients!
What is the general mechanism of action of the anti-convulsant mood stabilisers?
- Reduce abnormal electrical activity in brain via
- inhibition of voltage-sensitive Na+ channels leading to
- reduced influx of Na+ ions, preventing
- neurons from depolarisation and therefore generation of Action Potential
- These can be ‘use-dependent’-more effective at blocking channels in areas of the brain where action potentials are firing repetitively
How else does Carbamazepine work?
- (other than stabilisation of neuronal membranes via inhibition of voltage-sensitive ion channels)
- has the ability to inhibit polysynaptic responses?
How else does Lamotrigine work?
- It also inhibits the Ca+ dependent presynaptic release of excitatory NTs such as glutamate
- Newer!
How else do the Sodium Valproates work?
Indirectly by increasing GABA activity. GABA is an inhibitory NT (think Benzos)-Cl ions, hyperpolarisation, inhibit neuronal transmission, reduced chance of AP, exerts stabilising influence, thereby decreasing excessive activity
They do this by;
- enhancing availability of GABA in synaptic cleft
- through inhibition of 2 enzymes responsible for GABA inactivation
- enhancing postsynaptic action of GABA
- through enhancing opening of receptors
What are the contraindications common to all mood stabilisers?
- Pregnancy
- Renal Impairments
- Suicidal thoughts
What are the contrainidications for Lithium?
- Cardiovascular disease
- Hyperthyroidism
- Addison’s/Brigada Disease
- ECT
- Diuretics or people with sweating/diarrhoea
What are the contraindications for the Sodium Valproates?
- MAOIs or APs
- Hepatic dysfunction
What are the contraindications for Carbamazepine?
- Chemically related to TCAs, so not if allergic
- Many drug interactions (TCAs, MAOIs, APs, other anti-seizure drugs)
- St John’s Wort
- decrase oral contraceptive efficacy
- Heart Conditions
- no alcohol
- no grapefruit
What are the contraindications for Lamotorgine?
- Parkinsons
What are the side effects of lithium?
adverse effects linked to serum levels
- Tremors
- Weight gain
- GI upset-constipation/diarrhoea
- Polyuria/polydipsia
- metallic taste
What are the side effects common to anticonvulsants generally?
- Indicators of disorders of
- Blood (anaemia, bone marrow suppression)
- Liver (hepatitis)
- Skin (Stevens-Johnson syndrome)
- GI disturbances
- Fatigue
What are the additional side effect of the Sodium Valproates?
- Weight Gain
- Hair Loss
What are the additional side effects of Carbamazepine/Lamotrigine?
- Water retention and hyponatraemia
Why might we talk of polypharmacy with regards to Bipolar disorder?
Use of mood stabilisers often accompanied by;
- antidepressant (depressive episodes)-too much can trigger elation/mania
- anxiolytics to calm (manic episodes)
- hypnotics for insomnia (severe episodes)
- antipsychotic (psychosis during manic episodes)
Tell me about the special monitoring requirements for Lithium (please)
- Weekly blood tests until falls within safe range of 0.4-1.0mmol/L then 3 monthly tests-note, must be 12 hours after dose
- Renal, cardio and thyroid function baseline then 6 monthly
- Purple Lithium treatment pack (including blood test result booklet, lithium therapy info booklet and lithium alert card)
Lithium Patient Education Pertinent Points?
- Lots of things affect Lithium levels (metabolic rate, weight, salt intake, exercise levels and fluid consumption)-it is your responsibility to maintain these to keep you levels stable within safe range.
- If adjusted and levels fo above 1.5 mmol/L, risk of Lithium Toxicity!
- can occur at any time + fatal, symptoms include;
- blurred vision
- difficulty walking
- slurred speech
- irregular heartbeat
- rash, legs/feet + hands/arms (muscle twiches, swollen, trembling)
What are the options regarding pregnancy and mood stabilisers?
- Lithium
- high risk of heart defects + still-births
- no breastfeeding
- levels erratic during pregnancy and childbirth-much increased monitoring
- Anticonvulsants
- ‘fetal anticonvulsant syndrome’
- develomental delay
- first three months = worst
- breastfeeding okay
- Valproate
- as of April 2018-contraindicated in women of child bearing age because of teratogenic risks. (only prescribed for epilsepy if no suitable alternate treatment and enrolled on Pregnancy Prevention Programme)
How is Lithium absorbed, excreted and distributed?
- Absorbed in GI tract
- Peak at 2-4 hours
- excreted from kidney, + 80% reabsorbed (during dehydration/sodium dehyradation, more reabsorbed into serum-toxic!)
- Same distribution in body as water
How are the anticonvulsant mood stabilisers absorbed, metabolised and excreted?
- All readily absorbed from GI tract, metabolised in liver and excreted in urine
- All different durations of action
