Alpha blockers (also commonly known as the alpha-adrenergic antagonist) are used for the treatment of a number of conditions like Raynaud’s disease, benign prostatic hyperplasia and hypertension. This drug class tends to cause relaxation of some muscles and assist in the dilation of the small blood vessels. Alpha blockers produce its action by inhibiting norepinephrine from causing the constriction of muscles inside the walls of small veins and arteries. As a result the vessels stay dilated and relaxed ultimately controlling the high blood pressure across the vessel walls.
What Are Alpha Blockers Used For?
An alpha blocker is commonly prescribed for the following conditions:
- Benign prostatic hyperplasia also known as enlarged prostate
- Raynaud’s disease
- Scleroderma which is characterized by thickening and hardening of skin
- Pheochromocytoma, a tumor of adrenal gland
Even when they are indicated for the treatment of hypertension, alpha blockers aren’t really the first choice of drug class for the condition and are often given along with other drugs like diuretics.
Alpha Blockers Examples and List
Given below is the alpha blockers list that includes both selective and non-selective alpha blocker drugs.
The selective alpha blockers include following drugs:
- Doxazosin- used for benign prostatic hyperplasia and hypertension
- Silodosin- used for benign prostatic hyperplasia
- Prazosin- used for hypertension
- Tamsulosin- used for benign prostatic hyperplasia
- Alfuzosin- used for benign prostatic hyperplasia
- Terazosin- used for benign prostatic hyperplasia and hypertension
- Yohimbine- used to relieve vasoconstriction associated with Reynaud’s disease
The non-selective alpha blockers list comprises of following drugs:
- Phenoxybenzamine- used for pheochromocytoma, hypertensive crisis, and sometimes Reynaud’s disease
- Phentolamine- used for short term management of pheochromocytoma
A single daily preparation of terazosin or doxazosin is often recommended to treat hypertension. These preparations promote patient compliance as there is less clutter and more ease and patient can easily remember to take them once daily. HoweverPrazosin require multiple dosing each day like 2-3 times. Prazosin can produce a significant decline in blood pressure after the intake of first dose.
A single daily preparation of terazosin, Tamsulosin, Doxazosin or Alfuzosin is often recommended to treat benign prostatic hyperplasia. The single daily dosing is less likely to cause that many side effects which result from multiple dosing.
Alpha Blockers Side Effects
However these drugs come with their own side effects and certain cautions must be taken:
An alpha blocker may produce a ‘first-dose-effect’ i.e. the blood pressure drops several points and the patient may feel dizzy and faint after rising from a lying or sitting position. For this reason it is recommended to take the first dose at bedtime.
The other side effects that this class of drug may produce include:
- Weight gain
- Slight decline in the levels of LDL ( low density lipoproteins) and cholesterol
- Pounding heartbeat
These drugs may interact with other drugs by either increasing or decreasing their effects, when taken together. If the doctor prescribes you an alpha blocker, be sure to inform your doctor if you are already on other drugs like calcium channel blockers, beta blockers or drugs used for erectile dysfunction (ED)
Few researches suggest that long-term use of alpha blockers may put you at risk of having a heart failure. However more research is required to make this finding authentic, but you can always talk to your doctor if you have any concerns related to your treatment regimen.
Who Should Not Be Prescribed Alpha Blockers?
Under certain circumstances, alpha blocker is not prescribed to women because it tends to cause stress incontinence and diminishes the control over bladder. All those women who are trying to get pregnant or are already pregnant or nursing their babies must take these drugs only upon doctor’s recommendation based on the risk-benefit ratio. They are also contraindicated in people with:
- Postural hypotension (or in people who faint after urinating)
- Heart failure
- Parkinson’s disease
- Compromised hepatic or renal function
Other Medications for High Blood Pressure
As discussed earlier, alpha blockers aren’t the drugs of choice in case of hypertension and are only given when the other anti-hypertensive agents have failed to produce the desired effect. The drug classes that are given more preference over alpha blockers for treating hypertension include ACE inhibitors, beta blockers, diuretics and calcium channel blockers.
- Thiazide diuretics: they work by expelling out sodium and water from the body by minimizing their retention and ultimately decreasing the blood volume which in turn controls high blood pressure. They are often considered the first choice of drug class but may also be given in combination.
- Beta blockers: they produce their action by dilating the blood vessels and minimizing the cardiac workload. This results in slow beating of heart with minimum force. They aren’t that effective when given alone especially in elderly patients. However when given in a combination with other anti-hypertensive drugs, they may produce just the desired effect.
- ACE inhibitors: they produce their effect by inhibiting the conversion of angiotensin I into angiotensin II, as a result of which the blood vessels undergo dilation and relaxation. These are drugs of choice in case of chronic kidney disease along with hypertension.
- ARBs: angiotensin II receptor blockers assist in dilation of blood vessels by inhibiting the function of naturally existing chemical, angiotensin II, that under normal conditions cause the constriction of the blood vessels. These are drugs of choice in patients with chronic kidney disease along with hypertension.
- Calcium channel blockers: they produce their action by relaxing the muscles present within the blood vessels. They are more preferred in elderly patients. These drugs may interact with grapefruit.
- Rennin inhibitors: they produce their action by slowing the production of renin that initiates series of reactions which ultimately result in high blood pressure. So with its production declining, renin won’t be able to initiate these reactions.
- Central acting agents: they produce their effect by preventing the brain from giving signals to the nervous system to escalate the heart rate and constrict the blood vessels.
- Vasodilators: they produce their action by dilating and relaxing the muscles present within the walls of arteries, thereby keeping the arteries from constricting.
- Aldosterone antagonist: they produce their action by blocking Aldosterone that causes salt and water retention which ultimately promotes high blood pressure.