Chapter 4 - Nervous System Flashcards
Why avoid drugs acting on voltage gated sodium channels (e.g. Carbamazepine) in myoclonic epilepsy? What can be used instead?
May exacerbate by drugs with this MOA.
Sodium valproate
Leveitracetam / topirimate
Why avoid antipsychotics in elderly Alzheimer’s patients displaying non cognitive symptoms?
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
Why would a rash be if concern in a patient taking Galantamine?
Could potentially be SJS or exanthematous pustulosis.
Why monitor cholinergic effects and body weight in a patient changing from from oral to transdermal Rivastigmine?
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)
Why should patients on antiepileptics look out for fever, rash, lymphadenopathy, liver dysfunction, blood/renal/hepatic abnormalities?
These are signs of antiepileptic syndrome and can result in multi organ failure. Cross sensitivity can be an issue.
Why would a pregnant woman on Carbamazepine/ Phenobarbitol/Primodone be prescribed folic acid?
To prevent neural tube defects if anti epileptic has not been withdrawn due to unplanned pregnancy. These are teratogenic in first trimester.
Why screen for HLAB 1502 allele for Chinese patients being started on Carbamazepine, Eslicarbazepine, Fosphenytoin and Phenytoin?
Increase risk of SJS.
Why consider vit d supplementation in patients Phenobarbitol, sodium valproate and Phenytoin?
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.
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?
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
Why would you be wary of benzos and alcohol?
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
Why might you discontinue a patient on Dexamfetamine, Lisdexamfetamine, and methylphenidate?
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.
Why might you need to withdraw Guanfacine from a patient?
Excessive bradycardia, QT elongation, CVD or hypokalaemia or somnolence.
Four main counselling points for Valproic acid?
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.
Examples of hepatotoxic drugs to use with caution in sodium valproate and valproic acid?
Statins Paracetamol ‘Cyclines Methotrexate Mercaptopurine Clavulinic acid Flucloxacillin Alcohol Vincristine Sulfasalazine
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
?
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.
A patient is prescribed phenelzine as third line anti depressant, why would you counsel them about diet?
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).
Why would you recommend Moclobemide over Tranylcypromine?
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%.
When would a MAOI be contra-indicated?
Manic phase of BPD (like with all antidepressants) and phaemochromocytoma
When would you prescribe an MAOI with caution?
HT
Epilepsy
DM
A patient on Isocarboxazid enters a manic phase, how would you advise withdrawal?
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.
MAOIs have many interactions, give examples of those increasing the following: Serotonin syndrome Hypertension Hypotension CV
Ss - Amfetamines, Fentanyl, Lithium, Bupropion, triptans, SSRIs
Hypertension - Levodopa, Methylphenidate
Hypotension - TCAs, B blocker, Levodopa
CV - SABA and LABA.
Why would you prescribe an SSRI, or Trazodone over TCAs (Amitripyline, Clomipramine, Dosulepine, Doxepin, Imipramine, Lofepramine, Nortriptyline, Trimipramine.
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
Why might a patient complain of breast pain whilst taking a first gen antipsychotic (Chlorpromazine, Levopromazine, Promazine) and how could this be dealt with?
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.
Why are the ergots Bromocriptine and Cabergoline avoided normally?
Associated with fibrotic disorders - pulmonary fibrosis, retroperineal fibrosis and pericardial fibrosis as well as being associated with impulse control disorders.
