Psychotropic medication includes some of the most commonly prescribed medication in the the world. This article will cover the types of medication you will tend to encounter, important side effects, monitoring and emergencies.

Mood disorders

When initiating patients on anti-depressant medication it is important to follow them up within 2 weeks. This is because one of the earliest benefits is an increased motivation, which can paradoxically increase the risk of suicide.

Antidepressants

• SSRIs (selective serotonin reuptake inhibitors) e.g. sertraline, citalopram, fluoxetine (1st line in <18), paroxetine
• SNRIs (serotonin noradrenaline reuptake inhibitors) e.g. venlafaxine, duloxetine
• NaSSA (noradrenergic and specific serotonergic antidepressant) e.g. mirtazapine
• TCAs (tricyclic antidepressants) e.g. amitriptyline, gabapentin – these are not recommended to be used due to risk in overdose.

NB: antidepressants are also indicated in anxiety and eating disorders.

Lithium

• Indication: bipolar affective disorder (BPAD), severe depression
• Forms: lithium carbonate or citrate
• MOA: not fully understood – permeates voltage-gated Na⁺ ATPase channels
• Has a very narrow therapeutic index (0.4-1.0mmol/L) so must prescribe by same brand and form, and advise on regulating hydration status
• ADRs:
  • Common: metallic taste, GI upset, fine tremor, polydipsia, polyuria
  • Notable: weight gain, acne, hypothyroidism, nephrogenic diabetes insidious, hypercalcaemia (due to increased PTH)
  • Serious: arrhythmia (T wave flattening), risk of toxicity
• Monitoring:
  • Baseline: ECG, blood tests (FBC, U&Es, LFTs, TFTs, bone profile)
  • Serum lithium: take level 12 hours after dose – 1 week after initiation/dose change then weekly till stable
  • 6 monthly: U&Es, TFTs, bone profile

Other mood stabilisers

• Semisodium valproate:
  • Used for manic episodes of BPAD
  • ADRs: GI upset, weight gain, hepatotoxicity, acute pancreatitis
  • Teratogenic – neural tube defects
• Carbamazepine:
  • Used for rapid cycling BPAD
  • ADRs: GI upset, agranulocytosis, SIADH, Stevens-Johnson syndrome
• Lamotrigine:
  • Used for depressive episodes associated with BPAD
  • ADRs: GI upset, fatigue, blurred vision, Stevens-Johnson syndrome
  • Teratogenic – oral cleft defects

Antipsychotics

• 1st gen ‘typical‘: haloperidol, zuclopenthixol, chlorpromazine
• 2nd gen ‘atypical‘: olanzapine, risperidone, quetiapine, clozapine
• 3rd gen ‘atypical‘: aripiprazole

ADRs

• Common: GI upset, sedation, postural hypotension
• Notable: metabolic disturbance (weight gain, dyslipidemia), sexual dysfunction (hyperprolactinemia), extrapyramidal side effects
• Serious: QT prolongation, decreased seizure threshold, neuroleptic malignant syndrome

‘Atypical’ antipsychotics have a higher affinity for 5-HT2A receptors and a lower affinity for D2-like (dopamine) receptors making extrapyramidal side effects milder and therefore being the preferred agent. Aripiprazole is considered a 3rd-gen atypical antipsychotic as it is a newer drug and a partial D2 agonist, so tends to have the least side effects.

Monitoring

• Before starting: assess cardiovascular risk
• Baseline: BMI, BP, ECG, bloods (FBC, HbA1c, U&Es, LFTs, TFTs, CK, prolactin)
• Blood tests should be monitored every 6 months

Clozapine

• ‘Atypical’ antipsychotic used in treatment resistant schizophrenia
• Unique ADRs: agranulocytosis, constipation, myocarditis, hypersalivation, nocturnal enuresis
• Requires re-titration if missed 2 days of dosing
• Has unique FBC monitoring due to risk of agranulocytosis – must monitor FBC weekly for 18 weeks then fortnightly till a year

Emergencies

Lithium toxicity

• ABCDE – involve ITU and notify liaison psychiatry
• History + neurological examination
• ECG
• Bloods: U&Es, TFTs, serum lithium:
  • Serum lithium >1.5mmol/L: coarse tremor, weakness, drowsiness
  • Serum lithium >2.0mmol/L: hyperreflexia, seizures, renal failure
• IV volume replacement if mild/moderate, haemodialysis if severe

Serotonin syndrome VS Neuroleptic malignant syndrome

Written by: Dr Muhammad Zain Haq, Psychiatry Lead (F2)
Reviewed by Dr Patrick Ezeani (Consultant Psychiatrist)