We should be lucky to be living in the modern world where a lot of medical issues in the past can be treated well in the present. There are a lot of medicines available to treat the many health issues and we should be fortunate enough to know most medicines now are considered safe. In this article, we will be learning about one of the many medicines used to treat conditions associated with the kidney, known as aliskiren.
First thing first, what exactly is aliskiren? Aliskiren belongs to a group of drug classes known as renin inhibitors. To understand more about renin inhibitors, it will be better to know what renin itself is. Renin is an enzyme responsible for maintaining blood pressure and the level of sodium and potassium in the body. It is produced in the kidney and released to the bloodstream especially when the blood pressure is too low or depletion of sodium in the body. This is due to receptors sensitive to pressure called baroreceptors in the artery detecting severe fall of the blood pressure. Renin is also released due to the low sodium level detected by kidneys and activity in the sympathetic nervous system detected by receptors called beta 2 adrenergic receptors.
When renin is released, it stimulates formation of angiotensin in blood and tissues which ultimately lead to release of aldosterone from the adrenal cortex of the kidney. Angiotensin causes narrowing of the blood vessels while aldosterone causes the kidney to retain water and salt. This chain of mechanisms called a ‘renin-angiotensin-aldosterone pathway’ helps to increase the amount of fluid in the body which subsequently causes high blood pressure to increase.
Back to the our main focus of aliskiren, as a renin inhibitor, it displaces the site where the renin works and inhibits the ability of renin from stimulating the formation of angiotensin. Now that you know roughly how renin works and how renin inhibitors such as aliskiren work, you may wonder what this medicine is used for? In most cases, it is used to treat hypertension or you may be familiar with the term “high blood pressure”. It may be used as a single medication or be combined with other antihypertensive drugs. Hypertension is defined as the systolic blood pressure values of above 130 mmHg and/or diastolic blood pressure more than 80 mmHg. The systolic pressure is a result of a pressure from a force as the heart pumps blood into the arteries and diastolic blood pressure is a result of the heart resting between beats. Essential hypertension is defined as long-standing high blood pressure with no known causes. Primary hypertension is another term for essential hypertension.
Aliskiren is usually available as a 150 mg or 300 mg tablet. Patients are usually put on this medication with an initial dose of 500 mg daily. This dose may be increased to 300 mg daily when needed. It is important to take aliskiren as instructed by the doctor. Taking more than 300 mg daily does not show any further lowering blood pressure effect. Furthermore, taking it excessively increases chances for diarrhoea. Aliskiren may also be available in combination with other antihypertensive agents such as amlodipine and hydrochlorothiazide.
It is best to take aliskiren at the same time of the day to help patients remember to take it regularly. This medication can be taken before or after meal. Patients need to continuously take aliskiren despite feeling well. Never stop taking aliskiren unless instructed otherwise by a doctor. Should there be any side effects or feeling worse after taking aliskiren, patients need to discuss the matter with their doctor.
Similar to many other medications treating hypertension, aliskiren do have potential side effects. However, patients need to understand that doctors will always prescribe medication that provides benefits with consideration of the side effects. Common side effects of aliskiren are diarrhoea, headache, cough, dizziness and rash. If these side effects get severe or do not disappear, patients need to notify their doctor. Serious side effects such as anaphylactic reactions (severe allergic response characterised by difficulty breathing, difficulty swallowing, lethargy and losing consciousness)and low blood pressure, should be considered as emergencies and patients need to visit the emergency room.
If patients have other medical conditions such as diabetes, they need to let their doctor be aware of this condition. This is because aliskiren should not be used in patients with diabetes and taking ACE inhibitors or ARB. Patients with or used to have kidney disease or heart problems may need to avoid aliskiren as medications for these conditions may react badly with aliskiren. While there is no specific food to avoid, patients need to avoid drinking or food containing grapefruit juice and avoid supplements containing St John’s wort. Patients are advised to avoid eating meals high in fat right after taking aliskiren. Patients may want to avoid using salt substitutes containing potassium or using potassium supplements without getting medical advice from their doctor.
