Problem
Brian is a 67 year old male with a history of hypertension that has been treated for a number of years with the angiotensin converting enzyme (ACE) inhibitor enalapril. he has made several visits to the health centre over the past 6 months and on each occasion his blood pressure has been higher than expected. The GP decides to change his medication to a combination tablet of enalapril (20 mg) and hydrochlorothiazide (6 mg) once daily, and advises Brian that the combination drug contains diuretic.
1) Discuss the effect of the combination of an ACE inhibitor and a diuretic on renal haemodynamics.
2) Brian remains well for several months but on his latest visit he complains of pain and inflammation of his right big toe joint. He indicates that he is unable to sleep because of the pain.
Explain how hydrochlorothiazide may have contributed to Brian's problem
3) Brian tells the GP that because his toe was so painful he has taken for the last 5 days some of his wife's prescribed non-steroidal anti-inflammatory drugs (NSAIDs). The GP takes Brian's blood pressure, which is elevated, advises Brian that he should not have taken the NSAIDs and immediately orders some renal function tests.
Why is the GP concerned about Brian taking a NSAID? Consider in your response Brian's elevated blood pressure and the need for renal function tests.