Musculoskeletal system Flashcards
common indications for allopurinol (3)?
- prevent recurrent attacks of gout
- prevent uric acid and calcium oxalate renal stones
- prevent hyperuricaemia and tumour lysis syndrome
MOA of allopurinol?
xanthine oxidase inhibitor
(lowers plasma uric acid conc and reduces precipitation of uric acid in joints and kidneys)
adverse effects of allopurinol (2)?
can trigger or worsen acute attack of gout
skin rash (common- can be mild or more serious hypersensitivity reaction i.e. Stevens-johnsons syndrome)
allopurinol should NOT be started under which conditions (3)?
- acute attacks of gout
- recurrent skin rashes
- signs of severe hypersensitivity
allopurinol dose should be reduced in pateints with what conditions (2)?
renal impairment
hepatic impairment
allopurinol is metabolised in the ____ and excreted by the _____?
liver
kidneys
co-prescription of allopurinol with which drugs increases risk of (1) hypersensitivty and (2) skin rash?
ACE inhibitors/ thiazides
amoxicillin
how is allopurinol prescribed (start dose and titration)?
taken orally w a low start dose and then titrated up according to serum uric acid conc
when starting allopurinol for gout what should be co-prescribed?
NSAID e.g. naproxen
or/ colcochine
when allopurinol is used as part of cancer treatment it should be given before/after commencing chemotherapy?
before chemotherapy
when should allopurinol be taken in the day?
after meals
pts should be encouraged to maintain good fluid intake (2-3litres)
how could you communicate allopurinols purpose to the pt?
reduce attacks of gout (or formation of kidney stones)
if they develop a rash seek medical advice!
how should allopurinol use be monitored?
serum uric acid conc at 4 weks after starting Tx
(aiming for uric acid conc to < 300umol/L)
treatment with which drugs can increase serum uric acid conc causing gout (3)?
thiazides
loop diuretics
aspirin inhibits renal excretion of uric acid and can trigger acute attack
(should always consider drug-induced gout as a cause of new onset joint pain in these pts)
mesalazine and sulfasalazine belong to which drug class?
aminosalicyates
common indications for mesalazine and sulfasalazine (2)?
- mesalazine is first line for mild UC
- sulfasalazine is an option for managing RA
sulfasalazine is a DMARD- what does this stand for?
Disease- Modifying AntiRheumatic Drug
MOA of mesalazine and sulfasalazine?
release 5-aminosalicyclic acid (5-ASA)
(has anti-inflammatory and immunosuppressive effects)
side effects of mesalazine and sulfasalazine (
GI upset and headache (common)
blood abnormlaities (rare but serious)
renal impairment
sulfasalazine can also cause oligospermia in men
lasalazine and sulfasalazine are salicylates like which other drug?
aspirin
pts with aspirin hypersensitivity should not take these drugs
common indications for azathioprine (3)
- maintainance of remission of Crohns and UC
- DMARD in RA and autoimmune conditions
- prevent organ rejection in transplant recipients
what is the main metabolite of azathioprine and its MOA?
6-mercaptopurine
(inhibit synthesis of purines therfoer inhibiting DNA and RNA replication)
which enzymes are involved in the metabolism and elimination of azathioprine (2)?
xanthine oxidase
thiopurine methyltransferase (TPMT)
adverse effects of azathioprine (4)?
nausea (common)
hypersensitivity (D&V, rash, fever, myalgia)
bone marrow suppression (v serious)
hepatotoxicity/ inc tumour risk i.e. lymphoma (rare but serious)
what test should be performed before starting azathioprine therapy?
TPMT phenotyping
those with absent TPMT activity should not recieve prescription (those w low activity should only be treated by specialist)
dosage of azathioprine should be reduced in what circumstances (2)?
hepatic and renal impairment
is azathiprine safe in pregnancy?
unclear- shoul dnot be initiated in pregnancy but can be continued in those already established on Tx where benefits outweigh risk
is azathioprine safe to be coprescribed with allopurinol?
No- reduce metabolism of azathioprine and inc risk of toxicity
how is azathiorpine administered?
oral (preferred) and IV (should be diluted and given as infusion)
pts taking azathioprine should seek urgent medical advice if the develop the following (3)?
sore throat/fever (infection)
bruising/bleeding (low platelet count)
D&V/abdo pain (hypersensitivity)
how should azathiorpine be monitored?
FBC weekly for first 4 weeks and 3 monthly thereafter
common indications for calcium and vitamin D (5)?
- osteoporosis
- chronic kidney disease
- severe hyperkalaemia (calcium)
- hypocalcaemia
- vitamin D deficiency (rickets and osteomalacia)
why does the body require calcium?
essential for normal function of muscle, nerves, bone and clotting
how is calcium homeostasis managed?
parathyroid hormone and vitamin D
calcium and vitamin D should be avoided under which circumstances?
hypercalcaemia
oral calcium reduces the absorption of which drugs (4)?
iron
biphosphonates
tetracyclines
levothyroxine
Calcium administered IV should never be allowed to mix with what other substance?
sodium bicarbonate- risk of precipitation
how should pts with severe hyperkalaemia be monitored after admin of calcium gluconate?
12 lead ECG
what dose of calcium gluconate should be given as first line treatment in hyperkalaemia?
10mL calcium gluconate 10% IV over 5-10 mins
common indications for methotrexate (3)
- disease modifying for RA
- chemotherapy adjuvant
- severe psoriasis (inc. psoriatic arthritis)
MOA of methotrexate?
inhibits dihydrofolate reductase
has an antinflammatory and immunosuppressive effect
adverse effects of methotrexate (3)
mucosal damage (sore mouth, GI upset)
bone marrow suppression (neutropenia, inc risk of infection)
hepatic cirrhosis/ pulmonary fibrosis (long term effects)
is methotrexate safe in pregnancy?
No- teratogenic
men and women should use effective contraception for 3 months after stopping treatment
methotrexate is contraindicated in what condition?
severe renal impairment
should also be avoided in those with abnormal liver function
how often is methotrexate prescribed?
once weekly
what should be emphasised when explaining methrotrexate to the patient?
only taken once a week not daily
to seek urgent medical advice if they develop a sore throat/fever
how should methotrexate be monitored?
monitor symptoms- examine sore joints
blood tests for inflammatory markers
FBC, liver and renal function prior to Tx and 1-2 times weekly until established
2-3 times monthly thereafter
role of F1 in methrotrexate prescribing?
should NOT initiate prescription
may review and continue but always seek senior advice
examples of NSAIDs (3)?
naproxen
ibuprofen
etoricoxib
common indications for NSAIDs (2)
- ‘as needed’ for mild-moderate pain
- treat regular pain related to inflammation e.g RA
MOA of NSAIDs?
inhibit prostaglandin synthesis from arachidonic acid by inhibiting COX
adverse effects of NSAIDs (3)?
GI toxicity
renal impairment
inc risk of cardio event i.e MI/stroke
NSAIDs should be avoided under which circumstances (4)?
severe renal impairment
heart failure
liver failure
NSAID hypersensitivity
how long for NSAIDs before full antiinflammatory effect is seen?
3 weeks
to minimise GI upset how should NSAIDs be taken?
with or after food
how should NSAIDs be monitored?
assess symptoms
Biochemical if existing renal impairment
what should be considered as being coprescribed with NSAIDs paerticularly in those >65yrs ?
gastroprotection i.e PPI such as lansoprazole daily
common indications for paracetamol (2)?
- first line analgesic of acute and chronic pain
- antipyretic that can reduce fever
MOA of paracetamol?
poorly understood
weak inhibitor of COX/ weak antiinflammatory
paracetamol overdose causes what?
liver failure
in paracetamol overdose which toxic metabolite accumulates?
what does this result in?
NAPQI
(N-acetyl-p-benzopuinone imine)
hepatocellular necrosis
paracetamol dosing should be reduced in which pt groups (3)?
those w inc risk of liver toxicity (excess alcohol use)
reduced glutathione stores (malnutrition/low body weight (<50kg))
severe hepatic impairment
what is prescribed to combat paracetamol overdose?
acetylcysteine
when prescribing paracetmol what is important to check on the pts chart?
co-drugs such as co-codamol with ‘hidden’ paracetamol
common indications for quinine (2)?
- night-time leg cramps
- plasmodium falciparum malaria
adverse effects of quinine?
usually safe at recommended doses however potentially v toxic and fatal in overdose
tinnitus, deafness, blindness
GI upset
hypersensitivity reactions
hypoglycaemia
what effect does quinine have on the hearts rythym?
prolongs the QT interval and can predispose to arrythmias
quinines should be prescribed with caution in which pt groups?
those with hearing or visual loss
G6PD deficiency
pts takign drugs that prolong the QT interval (i.e amiodarone, antipsychotics, quinolones)
pregnancy
how should quinine be monitored?
after 4 weeks if no improvement in leg cramps stop prescription as unlikely to see any benefit
advise patient to report any hearing loss/ visual disturbance/ palpitations immediately
before starting quinine for nocturnal leg cramps what should be considered first (2)?
reversible causes- electrolyte disturbances / drug causes (statins)
non pharmacological management i.e passive stretching exercises
