Chapter 4 - Nervous System

Question 1

Why avoid drugs acting on voltage gated sodium channels (e.g. Carbamazepine) in myoclonic epilepsy? What can be used instead?

Answer 1

May exacerbate by drugs with this MOA.

Sodium valproate
Leveitracetam / topirimate

Question 2

Why avoid antipsychotics in elderly Alzheimer’s patients displaying non cognitive symptoms?

Answer 2

Increase risk of stroke, TIA and death (especially in risk groups like those with hypertension, DM,smokers, AF so should be limited to severe cases

Question 3

Why would a rash be if concern in a patient taking Galantamine?

Answer 3

Could potentially be SJS or exanthematous pustulosis.

Question 4

Why monitor cholinergic effects and body weight in a patient changing from from oral to transdermal Rivastigmine?

Answer 4

Rivastigmine can cause weight loss in patients so it is of concern if they are under 50kg (use with caution), although cholinergic effects like bradycardia, headache and increased salivation can occur treatment should be interrupted if GI issues occur (although GI issues less likely with TD)

Question 5

Why should patients on antiepileptics look out for fever, rash, lymphadenopathy, liver dysfunction, blood/renal/hepatic abnormalities?

Answer 5

These are signs of antiepileptic syndrome and can result in multi organ failure. Cross sensitivity can be an issue.

Question 6

Why would a pregnant woman on Carbamazepine/ Phenobarbitol/Primodone be prescribed folic acid?

Answer 6

To prevent neural tube defects if anti epileptic has not been withdrawn due to unplanned pregnancy. These are teratogenic in first trimester.

Question 7

Why screen for HLAB 1502 allele for Chinese patients being started on Carbamazepine, Eslicarbazepine, Fosphenytoin and Phenytoin?

Answer 7

Increase risk of SJS.

Question 8

Why consider vit d supplementation in patients Phenobarbitol, sodium valproate and Phenytoin?

Answer 8

Increased risk of osteomalacia in patients who have low sun exposure and / or low mobility.

Can advise on health, food sources include oily fish and eggs.

Question 9

Fosphenytoin has a faster onset and is less prone to site reactions than Phenytoin, making it preferable in status epilepticus use, what, however do you need to monitor for?

Answer 9

Cardiovascular reactions, for example asystole, fibrillation, cardiac arrest, heart block, hypotension can occur so BP, HR and respiration needs monitoring and patient to be observed for 30 minutes.

Dose reduction in hypotension, elderly and renal/hepatic impairment

Question 10

Why would you be wary of benzos and alcohol?

Answer 10

Both are CNS depressants, alongside cannabis, opioids, antihistamines, antipsychotics and antiepileptics leading to increased CNS depression so side effects like drowsiness, impaired concentration and confusion and amnesia will increase, thus could potentially affect breathing. The elderly tend to be at more risk

Question 11

Why might you discontinue a patient on Dexamfetamine, Lisdexamfetamine, and methylphenidate?

Answer 11

If the presences of tics or Tourette’s arises

Also if height and growth reducedbut this can be managed with a temporary drug free period (with a slow withdrawal to stop depression and anxiety)

Patients has suicidal ideation

Hepatic impairment

CVD

Medication has worsened epilepsy

Could be started on Atomoxetine or Guanfacine.

Question 12

Why might you need to withdraw Guanfacine from a patient?

Answer 12

Excessive bradycardia, QT elongation, CVD or hypokalaemia or somnolence.

Question 13

Four main counselling points for Valproic acid?

Answer 13

Contraception and teratogenic risk to foetus (developmental and congenital malformations)

Liver disease signs and symptoms. Be wary of hepatotoxic drugs,

Signs of pancreatitis

May need vitamin D supplementation.

Question 14

Examples of hepatotoxic drugs to use with caution in sodium valproate and valproic acid?

Answer 14

Statins
Paracetamol
‘Cyclines
Methotrexate
Mercaptopurine
Clavulinic acid
Flucloxacillin
Alcohol
Vincristine
Sulfasalazine

Question 15

Why counsel a patient on valproic acid to look out for the following:
Abdominal pain,nausea and vomiting

Abdominal pain, nausea, vomiting, pruritis, jaundice, oedema, malaise, drowsiness and reduced seizure control in epilepsy

?

Answer 15

The initial are signs of pancreatitis which requires medication discontinuation.

The latter are signs of liver disease and LFT would be performed at the start and at 6 months. Patients at higher risk are those with metabolic disorders, degenerative disorders, severe seizures, organic brain disease and on hepatotoxic drugs.

Question 16

A patient is prescribed phenelzine as third line anti depressant, why would you counsel them about diet?

Answer 16

The cheesing effect is a hypertensive effect leading to a throbbing headache and is associated with foods high in tyrosine / tyramine such as Bovril, Marmite, game, alcoholic, pickled herring, salami, broad bean (though this contains dopa), foods going off, mature cheese, yeast extracts and fermented soy extracts. This occurs when an MAOI such as Phenelzine, Isocarboxid or Tranylcypromine (even more common).

Question 17

Why would you recommend Moclobemide over Tranylcypromine?

Answer 17

It is meant to have a reduced potential of hypertensive affects and less food restrictions are required, although yeast extracts (like marmite), mature cheese and fermented soy should still be avoided.

This could potentially happen if patient also has an ulcer or needs acid reduction and is prescribed Cimetidine which requires Moclobemide does to be reduced to 33-50%.

Question 18

When would a MAOI be contra-indicated?

Answer 18

Manic phase of BPD (like with all antidepressants) and phaemochromocytoma

Question 19

When would you prescribe an MAOI with caution?

Answer 19

HT
Epilepsy
DM

Question 20

A patient on Isocarboxazid enters a manic phase, how would you advise withdrawal?

Answer 20

Ideally to be tapered over 4 weeks as withdrawal effects can occur within 5 days of stopping suddenly giving rise to agitation, ataxia, irritation, movement disorders, slowed speech and cognitive issues.

Question 21

MAOIs have many interactions, give examples of those increasing the following:
Serotonin syndrome
Hypertension
Hypotension
CV

Answer 21

Ss - Amfetamines, Fentanyl, Lithium, Bupropion, triptans, SSRIs

Hypertension - Levodopa, Methylphenidate

Hypotension - TCAs, B blocker, Levodopa

CV - SABA and LABA.

Question 22

Why would you prescribe an SSRI, or Trazodone over TCAs (Amitripyline, Clomipramine, Dosulepine, Doxepin, Imipramine, Lofepramine, Nortriptyline, Trimipramine.

Answer 22

Trazodone is TRA-like but safer in over dose, SSRIs are the safest in OD (still leading to altered mental states, autonomic dysfunction and neuromuscular acitivity) whereas TCAs are the greatest risk in suicidal patients due to hypothermia, coma, convulsions, respiratory failure, cardiovascular failure, cardiotoxicity and epilogenic effects

Question 23

Why might a patient complain of breast pain whilst taking a first gen antipsychotic (Chlorpromazine, Levopromazine, Promazine) and how could this be dealt with?

Answer 23

First gen as well as Risperidone and Amisulpride can cause hyperprolactinaemia leading to breast pain, enlargement, milk excretion, sexual dysfunction.

Patient could be changed to Ariprazole which reduces prolactin as it partial dopamine agonist.

Question 24

Why are the ergots Bromocriptine and Cabergoline avoided normally?

Answer 24

Associated with fibrotic disorders - pulmonary fibrosis, retroperineal fibrosis and pericardial fibrosis as well as being associated with impulse control disorders.

Question 25

Why would a patient presenting with involuntary facial movements whilst on Chlorpromazine be a cause for concern?

Answer 25

Tardive dyskinesia can be permanent and signs should result in treatment discontinuation.

Question 26

Why avoid more than one anti psychotic at a time preferentially?

Answer 26

Two or more anti psychotics increase the risk of QT elongation, extrapyramidal side effects A(parkinsonian, dystonia, dyskinesia, akathisia, tardive diskinesia) and could cause sudden cardiac death

Question 27

Why take care in patients on antipsychotics who have CVD?

Answer 27

Risk of arrhythmias, hypotension, QT elongation so BP and ECG monitoring required.

Question 28

Why would you use a first gen antipsychotic in DM over a second gen?

Answer 28

Second gen are associated with insulin resistance and so weight and blood lipids should be monitored

Ariprazole, Amisulpride are the least like in the second gen to do this.

Question 29

Why might you use a second gen ( Olanzapine, Risperidone) as a depot inject?

Answer 29

To increase adherence whilst minimising extrapyramidal side effects.

Question 30

Drugs associated with increased QT intervals?

Answer 30

Amiodarone
Amisulpride
Chlorpromazine
Citalopram
Clarithromycin
Quinolones

Question 31

Conditions predisposing a patient to QT elongation salary from QT prolonging drugs?

Answer 31

Hypokalaemia

Renal impairment / dysfunction

Question 32

Why would a patient on antipsychotics need to look out for muscle rigidity, increased temperature and confusion?

Answer 32

These are signs of antipsychotic malignant syndrome

Question 33

Why are acute porphyrias a Phenytoin contraindication?

Answer 33

Rare side effects of Phenytoin are Leucopenia, blood disorders, anaemia and thrombocytopenia.

Question 34

Why avoid Phenytoin in absence and myoclonic seizures?

Answer 34

Can do nothing or worsen

Question 35

Why avoid intramuscular Phenytoin?

Answer 35

Erratic absorption could result in therapeutic failure

Question 36

Why might the usual Phenytoin plasma concentration of 10-20mg/L be changed in the elderly, in the pregnant, HF, or children?

Answer 36

Altered (reduced protein plasma binding)

Might measure free plasma concentration instead of total

Question 37

Why would a Phenytoin patient on Salicylates, Phenylbutazone or Valproate require careful monitoring?

Answer 37

These compete for protein plasma binding, increasing plasma levels but also increase hepatic clearance so levels could either increase or decrease.

Question 38

Symptoms of Phenytoin toxicity?

Answer 38

Nystagmus
Diplopia
Slurred speech
Ataxia
Confusion
Hyperglycaemia

Question 39

Why might a patient who was switched to Phenytoin be stopped then reintroduced slowly at signs of rash?

Answer 39

If switched from anothe antiepileptic could potentially be cross sensitivity from antiepileptic syndrome leading to fever, rash, lymphadenopathy, liver dysfunction, haematological/renal/pulmonary abnormalities, vasculitis and potentially multi organ failure.