LITHIUM Flashcards

1
Q

What is lithium most commonly used for?

A

It is a mood stabilising drug that is used most commonly prophylactically in bipolar disorder but also as an adjunct in refractory depression.

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2
Q

What are the proposed mechanisms of action for lithium in mood-stabilisation?

A

Interferes with inositol triphosphate formation

Interferes with cAMP formation

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3
Q

How is lithium excreted?

A

Via the kidneys

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4
Q

What is therapeutic window for lithium?

A

Very narrow, hence why it is such a toxic drug that needs such close monitoring. Range is 0.4 - 1.0 mmol/L. It also has a very long plasma half-life.

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5
Q

What can affect lithium clearance from the body and lead to a build up of lithium to toxic levels?

A

Renal impairment

Sodium depletion - the kidney will hold onto lithium in place of sodium

Diuretics especially bendroflumethiazide

NSAIDs

ACE-inhibitors

Antipsychotics can synergistically increase lithium induced neurotoxicity

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6
Q

What are the side effects of lithium?

A

Polydipsia

Polyuria

Nausea/vomiting

Diarrhoea

Weight gain

Oedema

Fine tremor

Muscle weakness

Problems with concentration and memory

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7
Q

What are the complications of lithium therapy?

A

Nephrogenic diabetes insipidus

Thyroid enlargement, may lead to hypothyroidism

Precipitates skin problems eg psoriasis

Leucocytosis

Teratogenicity - Ebstein’s anomaly

Exacerbate myasthenia gravis

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8
Q

What are the clinical features of lithium toxicity?

A

Polydipsia

Polyuria

Coarse tremor

Hyperreflexia

Acute confusion

Seizure

Coma

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9
Q

What are the ECG changes associated with lithium toxicity?

A

T-wave flattening or inversion

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10
Q

How do we manage someone with mild-moderate lithium toxicity?

A

May respond to fluid resuscitation

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11
Q

How do we manage someone with severe lithium toxicity?

A

Haemodialysis

Sodium bicarbonate is sometimes used but there is limited evidence to support this. By increasing the alkalinity of the urine it promotes lithium excretion.

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12
Q

In which patients in lithium therapy contraindicated?

A

Breast feeding mothers

Relative contraindication for those on antipsychotics, NSAIDs, diuretics (bendroflumethiazide) and cardioactive drugs.

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13
Q

How are lithium levels monitored and what is the desired range?

A

Should be checked weekly until stable for 4 weeks and every 3 months thereafter

Levels taken 12 hours post-dose

Range should be 0.4 - 1.0 mmol/L

Patients should be issued with an information booklet, alert card and record book

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14
Q

As well as lithium levels, what else should be monitored in a patient on lithium for mood stabilisation?

A

Thyroid function

Renal function

ECG

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15
Q

What monitoring tests are needed for someone starting on lithium as treatment for bipolar affective disorder?

A

FBC

U+Es

TFTs

Pregnancy test

ECG

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