Pharmacology - Musculoskeletal

Question 1

Sulfasalazine

Mesalazine

Answer 1

• *Indications:** Mild to severe UC, active crohn’s, RA
• *MOA:** 5 ASA - unknown MOA
• *SE’s:** Sulfasalazine > mesalazine. Blood dyscrasias, hepatitis, rash, urticaria, oligospermia, pulmonary fibrosis, marrow suppression.
• *CI’s:** Salicylate allergy, caution in renal or hepatic impairment
• *Interactions:** NSAIDs
• *Other:** Monitor FBC. Better than methotrexate in young females with RA

Question 2

Methotrexate

Answer 2

• *Indications:** Cancer, RA, Psoriasis, Crohn’s
• *MOA:** Dihydrofolate reductase inhibitor → prevents cells from dividing
• *SE’s:** BM suppression, pulmonary fibrosis, hepatotoxic
• *CI’s:** Renal/liver impairment
• *Interactions:** Increased toxicity with NSAIDs, ciclosporin, steroids
• *Other:** Monitor FBC, LFTs

Question 3

Hydroxychloroquine

Answer 3

Indications: Active RA, SLE, discoid lupus
MOA: Decreases activation of dendritic cells → inhibits phospholipase A = antiinflammatory
SE’s: Visual change → rarely retinopathy, seizures, BM suppression
CI’s: Caution in G6PD deficiency
Interactions:
Other: Monitor vision

Question 4

Penicillamine

Answer 4

Indications: Wilson’s disease, AIH, cystinuria, severe active RA
MOA:? reduces IgM concentration, chelates copper + lead
SE’s: Neprotic syndrome, drug-induced lupus, taste change
CI’s: SLE
Interactions:
Other: Rarely used. Chelates copper + lead → prevents stones in cystinuria

Question 5

Infliximab (Remicade)

Answer 5

Indications: IBD, ankylosing spondylitis, RA, psoriasis
MOA: Chimeric anti-TNF mAb
SE’s: Severe infections, TB, allergic reactions, CCF, CNS demyelination, increased incidence of AI disease
CI’s: Active TB infection, pregnancy
Interactions:
Other: Screen for TB before use. Parenteral admin. Give with hydrocortisone to reduce allergic SE’s

Question 6

Colchicine

Answer 6

Indications: Acute gout
MOA:
SE’s: Diarrhoea, renal impairment
CI’s: Caution in renal impairment
Interactions:
Other:

Question 7

Allopurinol

Answer 7

• *Indications:** Prophylaxis of gout
• *MOA:** XO inhibitor
• *SE’s:** Severe skin reactions - EM → SJS, GI upset, hepatotoxic
• *CI’s:** Caution in renal + liver impairment - reduce dose
• *Interactions:** Decreases metabolism of azathioprine - avoid
• *Other:** Initial Rx can precipitate gout so initiate with NSAID + colchicine cover

Question 8

Feboxustat

Answer 8

Indications: Treatment of chronic hyperuricaemia in gout
MOA: XO inhibitor
SE’s: Headache, rash, abnormal LFTs, GI upset
CI’s: Caution in renal + liver impairment. Not Rx for acute gout
Interactions:
Other:

Question 9

Probenecid

Answer 9

Indications: Long term Rx of gout
MOA: Uricosuric - increase excretion of uric acid in urine
SE’s: GI upset
CI’s: Renal impairment - nephrolithiasis
Interactions:
Other:

Question 10

Rasburicase

Answer 10

Indications: Prophylaxis and Rx of acute hyperuricaemia with initial chemo
MOA: Recombinant uric oxidase
SE’s: Fever
CI’s: G6PD deficiency
Interactions:
Other:

Question 11

*least toxic*

Ibuprofen
Diclofenac
Aspirin
Naproxen
Indomethacin

*most toxic*

Answer 11

• *Indications:** Antiinflammatory / analgesia given in manay conditions
• *MOA:** Non-selective COX inhibitors → stop conversion of arachidonic acid to prostaglandins
• *SE’s:** Gastritis, PUD, reduced GFR, interstitial nephritis, papillary necrosis, hyperkalaemia, peripheral oedema, bronchospasm, hypersensitivity - EM→SJS
• *CI’s:** Renal or cardiac failure, PUD, severe hepatic impariment, atherosclerosis. Caution in the elderly and asthmatics
• *Interactions:** Increased bleeding with warfarin, increased toxicity with methotrexate, reduced effects of ACEIs + ARBs
• *Other:** Given with PPI for gastroprotection

Question 12

Celecoxib

Answer 12

• *Indications:** Analgesia / anti-inflammatory
• *MOA:** Selective COX-2 inhibitor
• *SE’s:** Increases cardiovascular events, renal SEs same as NSAIDs
• *CI’s:** IHD, cerebrovascular disease, renal/liver failure
• *Interactions:** Reduced effect of ACEIs + ARBs, increased toxicity of methotrexate
• *Other:** Assess CV risk before use. Only used in younger patients with intolerance to NSAIDs - short term use. 50% reduction in risk of bleeding / gastritis compared to non-selective COX inhibitors

Question 13

Pyridostigmine

Neostigmine

Edrophonium

Answer 13

Indications: Edrophonium = diagnosis of MG due to its very short half life. Pyridostigmine = Rx of MG - longer half life
MOA: Anticholinesterase → Increases ACh in synaptic cleft, enhancing neuromuscular transmission
SE’s: Cholinergic
CI’s: Asthma, intestinal/urinary obstruction
Interactions:
Other: