GASTROINTESTINAL SYSTEM

Question 1

What is the mechanism of action of Aminosalicylates

Answer 1

They work by inhibiting inflammatory mediators to prevent the inflammation of the intestinal wall. As well as this they can also have an effect on the synthesis of platelet activating factors - hence how is can cause blood dyscrasias.

Question 2

What are the most important side effects to be aware of with Aminosalicylates?

Answer 2

• Blood Dyscrasia - report signs of infection, bleeding, bruising etc.
• Diarrhoea (take extra care in patients with severe Ulcerative colitis)
• Nausea and vomiting - mainly with sulfasalazine. Mesakazine has enteric coating.
• Acute intolerance syndrome (abdominal pain, fever, severe headache, rash)

Question 3

Main cautions with Sulfasalazine

Answer 3

• G6DP deficiency (enzyme which can protect red blood cells from damage)
• history of asthma
• risk of hepatic toxicity

Question 4

Monitoring with Aminosalicylates

Answer 4

• Renal function before starting treatment and 3 months after starting and then annually during treatment (can cause inflammation of the renal tubules and cause renal impairment)
• FBC initially if necessary and after 3 months of treatment and potential blood dyscrasias.

Question 5

Ciclosporin can be sometimes be used in ulcerative colitis. What is the mechanism of action of this.

Answer 5

Immunosuppressant - It works by inhibiting the release of lymphokines, suppressing cell-mediated immune response

Question 6

What are some of the common interactions with Aminosalicylates

Answer 6

• Drugs which induce antiplatelet/blood thinning effect.
• ACE inhibitors (increased risk of nephrotoxicity)
• NSAIDS (increased risk of nephrotoxicity)
• other immunosupressants (methotrexate)
• all other drugs which increase risk of nephrotoxicity

Question 7

Safety and clinical consideration with ciclosporin

Answer 7

• Should be prescribed brand specific
• Contraindicated when used in the eye where there is a suspected infection.
• contraindicated when used systemically in malignancy, uncontrolled hypertension, uncontrolled infection.
• oral solution can be mixed with orange juice or apple juice if needed.

Question 8

Monitoring considerations for ciclosporin

Answer 8

• Bp & renal function twice before starting in dermatitis and psoriasis.
• LFTS
• U&Es - risk of hyperkalaemia in renal dysfucntion
• magnesium
• lipids before and after the first month of treatment

Question 9

Common interactions with ciclosporin

Answer 9

• Amiodarone and Digoxin - increases concentration of ciclosporin
• statins - ciclosporin increases exporsure of statins
• carbamazepine decreases concentration
• macrolides increase concentration
• DOAC - ciclosporin increases exposure
• azoles increase concentration
• Increaae risk of nephrotoxicity and hyperkalaemia when used with ACE inhibitors
• when used with drugs which increase risk of nephrotoxicity

Question 10

Azathioprine mechanism of action

Answer 10

Is an immunosupressive drug which works by inhibiting puring sunthesis crucial for DNA and RNA repair. this leads to reduced cell division (particular immune cells - B and T lymphocytes thus suppressing the immune system

Question 11

Cautions and common side effects of Azathioprine

Answer 11

• caution in reduced thiopurine methyltransferase activity (TPMT) as less of this increases risk of side effects
• common SE: bone marrow suppression, risk of infection - report signs, thrombocytopenia, pancreatitis, nausea early on.