Angiotensin-receptor blockers (ARBs, sometimes known as sartans), angiotensin-converting enzyme inhibitors (ACE-inhibitors) and direct renin inhibitors such as aliskiren. Combination of medicines from any two of these classes is not recommended and, in particular, ACE-inhibitors and ARBs should not be used concomitantly in patients with diabetic nephropathy.

Several large studies found that combination of an ARB with an ACE-inhibitor was associated with an increased risk of hyperkalaemia, kidney damage or low blood pressure compared with using either medicine alone.

Furthermore, no significant benefits from dual blockade were seen in patients without heart failure and benefits were thought to outweigh risk only in a selected group of patients with heart failure in whom other treatments were unsuitable

Where combination of these medicines (dual blockade) is considered absolutely necessary, it must be carried out under specialist supervision with close monitoring of kidney function, fluid and salt balance and blood pressure.