Question: Describe the mechanism of action of aliskiren. 

Context:
Preliminary assignment a direct renin inhibitor aliskiren enhances the diuretic, natriuretic and kaliyuretic effects of the drug. 
Aliskiren: An orally active renin inhibitor.
Optimization of this compound by Novartis led to the development of aliskiren - the only direct renin inhibitor which is clinically used as an antihypertensive drug.
Aliskiren is a new renin inhibitor of a novel structural class that has recently been shown to be efficacious in hypertensive patients after once-daily oral dosing.
Aliskiren is a direct renin inhibitor that interrupts the renin-angiotensin-aldosterone system (RAAS) at its rate-limiting step.
THE READER WILL GAIN: Aliskiren, the first approved renin inhibitor to reach the market, is a low-molecular-weight, orally active, hydrophilic non-peptide molecule that blocks angiotensin I generation. 
TAKE HOME MESSAGE: The DRI aliskiren is an effective antihypertensive agent that preliminary data suggests has a beneficial effect in CVD and CKD. 
Aliskiren is a novel molecule which blocks the renin-angiotensin-aldosterone system in its rate limiting step by renin inhibition.
After discovery of the first direct renin inhibitor, aliskiren, which blocks the renin-angiotensin-aldosterone system in the first rate limiting step, in addition to angiotensin-converting enzymes (ACE) and angiotensin-receptor blockers (ARB), renin has become an important target nowadays. 
Aliskiren, the first orally effective direct renin inhibitor, is an effective antihypertensive agent with distinctive properties including placebo-like tolerability, pharmacologic effects that persist after drug discontinuation, and a unique mechanism of action.
Aliskiren, the first direct renin inhibitor to reach the market, is a low-molecular-weight, orally active, hydrophilic nonpeptide. Aliskiren blocks Ang I generation, while plasma renin concentration increases because the drugs blocks the negative feed-back exerted by Ang II on renin synthesis.
Pharmacokinetics and pharmacodynamics of aliskiren, an oral direct renin inhibitor.
One drug that emerged from this effort is aliskiren, a direct human renin inhibitor that blocks the conversion of angiotensinogen to angiotensin I (Ang I).
With its unique mechanism of action, combining aliskiren with another RAAS-blocking agent that has a different mechanism of action may provide more comprehensive blockade of the RAAS, potentially conferring additional clinical benefits.
In the ALTITUDE trial the use of the direct renin inhibitor, aliskiren, was associated with hypotensive episodes and an excess of ischaemic stroke
Renin is the rate limiting enzyme of the RAAS and aliskiren is a highly potent and selective inhibitor of the human renin
Aliskiren, the first direct renin inhibitor to be approved for the treatment of hypertension, blocks the RAAS at its point of activation
With its unique mechanism of action, combining aliskiren with another RAAS-blocking agent that has a different mechanism of action may provide more comprehensive blockade of the RAAS, potentially conferring additional clinical benefits

Answer: Aliskiren is a low-molecular-weight, orally active, hydrophilic non-peptide molecule that blocks renin and consequential angiotensin I generation. Renin inhibition interrupts the renin-angiotensin-aldosterone system (RAAS).