chemotherapy

Question 1

allopurinol indications

Answer 1

• prevent recurrent attacks of gout
• prevent uric acid and calcium oxalate renal stones
• prevent hyperuricaemia and Tumour lysis syndrome pre chemo

Question 2

MOA allopurinol

Answer 2

• xanthine oxidase inhibitor. metabolises xanthine to uric acid. inhibiting = lower plasma uric acid and reduces precipitation of uric acid in the joints or kidneys

Question 3

SE allopurinol

Answer 3

• can trigger or worsen an acute attack of gout when starting . can be reduced by co prescribing NSAID or colchicine in initiation phase.
• skin rash or SJS or TENS
• allopurinol hypersensitivity syndrome = lofe threeatening - fever, eosinophilia, LNA, liver and skin issues

Question 4

When should allopurinol not be started

Answer 4

acute attacks of gout

Question 5

CI to allopurinol

Answer 5

• recurrent skin rash or signs of more severe hypersesntiivvity

Question 6

where is allopurinol metabolised and excreted

Answer 6

1. liver

2. kidneys

Question 7

reduced dose of allopurinol to which patients

Answer 7

renal impairment

hepatic impairment

Question 8

interactions of allopurinol

Answer 8

• azathioprines active metabolite mercaptopurinne is metabolised by xanthine oxidase therefore = increased risk of toxicity
• co prescribe with ace-i and thiazides increase risk of hypersensitivity reaction and with amoxicillin increases risk of skin rash

Question 9

what dose should you start allopurinol at

Answer 9

100mg daily

Question 10

when should you give allopurinol as part of cancer therapy

Answer 10

pre chemo

Question 11

when should allopurinol be taken

Answer 11

after meals

Question 12

what drugs can cause acute attacks of gout

Answer 12

• thiazodes, loops, low dose aspirin

Question 13

methotrexate indications

Answer 13

• DMRD for RA
• Chemo for ca - leukaemia, lymphoma and some solid tumours
• psoriasis that is resistant to other therapies

Question 14

MOA methotrexate

Answer 14

• inhibitis dihydrofolate reductase - prevents cellular replication
  also immunosupresses. and inhibits inflammatory mediators

Question 15

SE methotrexate

Answer 15

• mucosal damage, sore mouth, GI upset
• BM supression

hyepersenitivity reactions - hepatitis, pneumonitis

ltm use - hepatic cirrhosis, pulmonary fibrosis

OD - as once weekly dose normally

neuro effects 0 headache,s eizure, coma

• dose related effects with renal imapirment and hepatotoxicity

treat toxicity with folinic acid - and with hydration and urinary alkalinisation to enhance excretion

Question 16

CI methotrexate

Answer 16

• pregnancy
• need contraception men and women
• severe renal impairment

relative CI - abnormal liver function

Question 17

Interactions methotrexate

Answer 17

• NSAis, penicillins - inhibits renal excretion - leads to toxicity
• other folate antagonists
• risk of neutropenia is increased if given with clozapine

Question 18

what seretonin 5HT3 receptor antagonists are used as antiemetics

Answer 18

ondansetron

granisetron

Question 19

Indications 5HT3RAN , antiemetics

Answer 19

• N and v esp in general anesthesia and chemo

Question 20

MOA 5HT3RAN, antiemetics

Answer 20

blocks 5ht3r in chemoreceptor trigger zone. blocks 5ht release from gut which often stimulates the vagus nerve - activates vomiting by soleus nucleus

Question 21

why do Ondansetron and gansetron not work for motion sickness

Answer 21

• 5ht is not involved in comms between vestibular system and vomiting centre. - this is where motion sickness originates from

Question 22

SE ondansetron etc

Answer 22

• rare; constipation, diarrhoea and headaches

Question 23

what can 5h3ran do to the heart

Answer 23

• prolong QT interval - so do not give wiht other drugs that do this

Question 24

typical starting dose of ondansetron

Answer 24

4-8mg 12hrly oral or IV. 1hr if possible before anticipated settings e.g. general anesthesia