Musculoskeletal system - Aminosalicylates: mesalazine, sulfasalazine Flashcards
1
Q
Musculoskeletal system
Aminosalicylates: mesalazine, sulfasalazine
Common indications
A
- Mesalazine is used first-line in the treatment of mild-to-moderate ulcerative colitis; sulfasalazine is an alternative but has largely been replaced by mesalazine for this indication.
- Sulfasalazine is one of several options for the management of rheumatoid arthritis, in which it is used as a disease-modifying antirheumatic drug (DMARD), usually as part of combination therapy.
2
Q
Musculoskeletal system
Aminosalicylates: mesalazine, sulfasalazine
MOA
A
- In ulcerative colitis (UC), mesalazine and sulfasalazine both exert their therapeutic effects by releasing 5-aminosalicylic acid (5-ASA).
- mechanism of action of 5-ASA is unknown, has both anti-inflammatory and immunosuppressive effects, acts topically on the gut rather than systemically
- For this reason, 5-ASA preparations are designed to delay delivery of the active ingredient to the colon
- oral form of mesalazine comprises a tablet with a coating that resists gastric breakdown, instead releasing 5-ASA further down the gut.
- Sulfasalazine consists of a molecule of 5-ASA linked to sulfapyridine.
- bacterial enzymes break this link and release the two molecules
- Sulfapyridine does not contribute to its therapeutic effect in UC, but it does cause side effects
- replaced by mesalazine
- By contrast, sulfapyridine is probably active in rheumatoid arthritis, though its mechanism is unclear. Mesalazine has no role in rheumatoid arthritis.
3
Q
Musculoskeletal system
Aminosalicylates: mesalazine, sulfasalazine
Important adverse effects
A
- Mesalazine causes fewer side effects than sulfasalazine, these are gastrointestinal upset (e.g. nausea, dyspepsia) and headache
- Both drugs can cause rare but serious blood abnormalities (e.g. leucopenia, thrombocytopenia) and renal impairment
- In men, sulfasalazine may induce a reversible decrease in the number of sperm (oligospermia).
- can also cause a serious hypersensitivity reaction comprising fever, rash and liver abnormalities.
4
Q
Musculoskeletal system
Aminosalicylates: mesalazine, sulfasalazine
Warnings
A
- Mesalazine and sulfasalazine are salicylates, like aspirin.
- Patients who have aspirin hypersensitivity should not take these drugs.
5
Q
Musculoskeletal system
Aminosalicylates: mesalazine, sulfasalazine
Important interactions
A
- Mesalazine tablets with a pH-sensitive coating (e.g. Asacol® MR) may interact with drugs that alter gut pH.
- For example, proton pump inhibitors increase gastric pH so may cause the coating to be broken down prematurely
- Lactulose lowers stool pH and may prevent 5-ASA release in the colon
6
Q
Musculoskeletal system
Aminosalicylates: mesalazine, sulfasalazine
Practical prescribing
A
- patients with rectal or rectosigmoid ulcerative colitis, a mesalazine enema or suppository is generally recommended
- In an acute attack, this is taken once or twice daily for 4–6 weeks in an attempt to induce remission
- Decisions regarding choice of therapy in rheumatoid arthritis should be taken by a specialist.
7
Q
Musculoskeletal system
Aminosalicylates: mesalazine, sulfasalazine
Administration
A
- commonly used Asacol® foam enema requires thorough mixing before administration, by shaking the can vigorously for two 15-second periods
- Tablet forms of mesalazine should be swallowed whole; not chewed or crushed.
- C-reactive protein concentration and calculation of disease activity scores.
- For safety, renal function should be checked in patients receiving oral mesalazine, and full blood count and liver profile monitored in patients receiving sulfasalazine
