For ACE inhibitors, does the dose matter for protecting kidneys against nephropathy? For example, would 1.25mg ramipril achieve this? 5 mg lisinopril?
ACE-Inhibitors (Angiotensin Converting Enzyme inhibitors) are one of the mainstays of therapy in the treatment of high blood pressure, heart attack prophylaxis, and many additional cardiovascular indications. They have also been found to have renal (i.e. kidney) protective effects in both diabetics and non-diabetics, delaying or preventing the progression of kidney disease. The renoprotective effects of ACE-Inhibitors, such as Altace (ramipril), are mostly independent of blood pressure reduction.
In fact, many guidelines recommend the use of ACE-Inhibitors to slow the progression of kidney disease in both high risk patients with high blood pressure and in diabetic patients that don't have high blood pressure.
The exact mechanism of how ACE-Inhibitors is uncertain but a few theories have been proposed:
- ACE-Inhibitors increase blood flow in the kidney, dilating smooth muscle and arterioles.
- ACE-Inhibitors are thought to enhance the filtering membrane in the kidney.
- ACE-Inhibitors increase GFR (Glomerular Filtration Rate), one of the main indicators of kidney function.
The dose needed of ACE-Inhibitors to confer renoprotective effects is much less established than the dosing protocols to treat say hypertension, heart failure etc... One of the most studied ACE-Inhibitors in this regard is Altace (ramipril), which was the focus of a large analysis known as REIN (Ramipril Efficacy in Nephropathy). There was no one definitive dose that was concluded to confer the most benefit however. Studies in diabetic patients have utilized doses every dose there is...1.25 mg, 2.5 mg, 5 mg, and 10 mg once daily.
The general recommendation in regard to what dose of ACE-Inhibitors to use is to start with a low dose and titrate to response and tolerance. The most common ACE-Inhibitors used include the previously mentioned ramipril as well as lisinopril, enalapril and benazepril.