Central Nervous System Flashcards
What are the steps of the pain ladder?
Paracetamol
Paracetamol + Weak opioid
Paracetamol + strong opioid
+/- adjuvants
What are the main side effects of opioids?
Sedation and anxiolysis, respiratory depression (combination of opioids and alcohol is particularly dangerous) Cough suppression pupil constriction nausea and vomitting Constipation
Which kinds of pain are opioids effective on?
acute and cancer pain
effectiveness questionable in chronic non cancer pain
Not effective in neuropathic pain
What is one of the main issues with opioids
Highly addictive
What is opioid induced hyperalgesia
Enhanced pain in response to opioid
What is the first choice regular strong opioid?
Morphine, unless renal impaired
Why is morphine not indicated in renally impaired patients?
Because of active metabolite accummulation, Chronic kidney disease stage 3-5 or creatinine clearance below 30ml/min should not be used.
How would you start morphine dosing?
Morphine sulfate MR in two divided doses, rounded to the nearest 10mg. Then add morphine sulfate oral solution 1/6th of the total daily dose every 4 hours as required, rounded to the nearest 5mg
How can morphine be given in patients with swallowing impairments?
Morphine sulfate modified release capsules can be opened and the contents swallowed without chewing, contents can also be given via PEG tube.
How should you increase a patients morphine dose?
Remember to include breakthrough dose into the TDD. The new daily dose is the accumulation of these doses over the day. Calculate new breakthrough dose 1/6th of TDD and round to nearest 5mg.
What are NSAIDs
drugs that act to relieve inflammation but are not structurally related to corticosteroids. They are analgesics, antipyretics and anti-inflammatory drugs.
What are the common adverse effects of NSAIDs?
Platelet dysfunction, inhibition of COX1, gastritis and peptic ulceration, acute renal failure, sodium and water retention and oedema, analgesic neuropathy, prolongation of gestation and inhibition of labour, hypersensitivity
How does paracetamol work?
inhibition of prostaglandins
How are anticonvulsants/anti-epileptics used for pain relief?
carbamazepine, tricyclic antidepressants. Follow neuropathic pain ladder
Discuss the use of paracetamol at step 1 of the pain ladder
Generally safe at therapeutic doses up to 4g per day in adults orally.
Risk factors for hepatotoxicity: low body weight, elderly/frail, cardiac pulmonary or renal insufficiency, malnourished, alcohol misuse disorder, hep c. If eGFR less than 30ml/min/1.73m2 dose interval minimum of 6 hours. IV dose is weight adjusted
Discuss the use of NSAIDs for pain
CV/GI, Renal dysfunction risks. Assess risk vs benefit, use for shortest time possible, be aware of adverse effects, gi protection.
Small increased risk of thrombotic events, greater risk at higher doses and long term. Lower risk with naproxen or ibuprofen at low dose
Diclofenac: contraindicated in ischemic heart disease, peripheral arterial disease, cerebrovascular disease, congestive heart failure. Risk of GI event higher in older people, avoid a combination of NSAIDs. Can precipitate renal failure, increased risk of with hypovolemia, or concomitant administration with ACE inhibitors, ARB, diuretics
What are the 3 safe steps for starting an NSAID
3 SAFE STEPS: don’t use unless you have to, consider topical NSAIDs ahead of oral for osteoarthritis, if they have to be used then balance benefits and risks, use a safer drug at lowest effective dose for the shortest period of time, high priority for medications review, consider gastroprotection
What must be taken into account with codeine/hidryocodeine?
They have a ceiling effect
When should tramadol be prescribed?
Only if first line weak opioids arent tolerated as it interacts with other medications, can lead to low seizure threshold
What non-pharmacological statergies can be used for pain management?
Psychological based therapies, CBT, physical therapy, exercise, electrotherapy, accupuncture
Describe migraine
can have triggers, presents with aura, and one sided pain in the head usually.
Discuss management of migraines
Reduction of triggers, keep a headache diary, review medications that may cause headache, pharmaceutical treatments
What medications can exacerbate migraines?
Oral contraceptive, HRT, medication overuse
What pharmaceutical treatment can be offered for migraine?
simple analgesia, triptan + paracetamol or NSAID, or anti emetic if needed
What counselling points go alongside migraine therapy?
Advise that:
• Aim is to reduce frequency and severity of migraine symptoms, not complete remission or cure of migraine
• Acute treatment and avoidance of know triggers and lifestyle modification will still be required
• Consider pharmacological therapies such as propranolol, topiramate, amitriptyline, do not offer gabapentin
Which medications are used for the treatment of schizophrenia?
Chlorpromazine, haloperidol, pimozide, sulpride, trifluoperazine
Discuss clozapine related to schizophrenia
it is the main drug used for schizophrenia, has low extra-pyramidal symptoms, does not increase prolactin, causes sedation and weight gain but no movement disorders
What are the main side effects of clozapine
sedation and weight gain, blood dyscrasia, constipation, drooling
does clozapine cause blood dyscrasia
yes, it starts to attack cells in the bone marrow, and creates damaged blood cells leading to a dip in immunity
is clozapine smoking sensitive?
Yes, the dosage must be adjusted alongside smoking regime
What can be done if the patient experiences drooling with clozapine
Apply a hyoscine patch
What can clozapine be switched to if patients wish to get pregnant?
Haloperidol
What are the main side effects of risperidone
weight gain, EPS, lactation
What are the main side effects of olanzapine
sedation, weight gain, EPS
What can be done if risperidone causes elevated prolactin
change it to olanzapine
What monitoring is required with olanzapine?
It can interact with ciprofloxacin, cause weight gain and predispose diabetes, therefore baseline weight lipids and glucose levels should be taken
Why are SSRIs first choice for depression?
they are cheap, well tolerated, effective, safe in deliberate overdoses
how can you change SSRI?
taper down dose, before titrating up now medication
How is levodopa dosed?
lowest effective, has side effects of nausea and vomitting, which should be treated with domperidone
What is the purpose of modified release levodopa?
To avoid the motor complications associated with short duration of action
What should happen if dopamine agonists cause obsessive activities?
reduce dose of dompamine agonists
What should happen if parkinsons medication needs to be changed?
They should never be stopped abruptly.
How do you calculate pack years?
multiply the number of cigarettes smoked per day by the number of years the person has smoked
How should treatment of epilepsy be started?
low dose titration
What counselling points should be given to patients being started on anti-epileptics?
Levels can be affected by other medications, they should maintain a balanced diet and avoid excessive alcohol intake
What are the main pharmacokinetic interactinos with phenytoin/carbemazepine/phenobarbital?
Induction of metabolism of other anticonvulsants, warfarin, oral contraceptives
What are main counselling points for valproate
it is a good drug for most epilepsy, but disaster for child bearing women. It is a broad enzyme inhibitor associated with the increased concentration of other drugs. Can be affected by oral contraceptive
What are the main points to remember about carbemazepine?
it is used for complex, partial and generalised seizures, has a narrow therapeutic window, short half life
What are the main points to remember for phenytoin
Prescribed for partial or generalised seizure, narrow therapeutic window. must be monitored
What are the main points to remember for lamotrigine?
Lower doses required with sodium valproate, can cause steven-johnson syndrome. Slow titration over a few weeks required
What are key warnings with paracetamol?
In overdose, paracetamol can cause liver failure
When should the paracetamol dose be reduced?
In chronic excessive alcohol use, malnutrition, severe hepatic impairment, low body weight
Are there any important interactions with paracetamol?
CYP inducers such as phenytoin and carbamazepine
What counselling points should go with paracetamol?
Effects should be felt within 30 mins of taking dose, do not exceed maximum dose, take every 4 hours. No more than 8 tablets in a 24 hour period
When should NSAIDs be avoided?
severe renal impairment, heart failure, liver failure, NSAID hypersensitivity
What should be done if NSAID use is unavoidable in high risk patients?
Use safest NSAID at lowest effective dose for the shortest period of time
What should always be considered for patients being prescribed NSAID?
Gastroprotection - PPI
What are the main warnings with morphine?
doses should be reduced in hepatic failure, renal impairment, and elderly. Do not give in respiratory failure
What are key interactions with morphine?
Should ideally not be used with other sedating drugs such as antipsychotics, benzodiazepines, tricyclic antidepressants
How should you counsel a patient around morphine?
- counsel patient not to be worried about the stigma
- warn patients that dose may need to be increased/decreased and not to be alarmed
- explain how to take
- sickness (give metoclopramide)
- constipation (senna and good hydration)
- do not operate heavy machinery if drowsy
