Beta-3 adrenoceptors are the most common beta receptors which can be found in the smooth muscle cells of the bladder wall and their stimulation is thought to induce bladder relaxation.
Mirabegron is the first available beta -3 agonist with approval for use in patients with overactive bladder symptoms. Mirabegron can improve overactive bladder symptoms due to BPE. Your doctor may advise mirabegron in combination with other drugs. Mirabegron can cause high blood pressure. Your blood pressure should be checked before you start treatment and regularly monitored while you are taking this medication.
Alpha-blockers are a group of drugs which improve the symptoms and the flow of urine by relaxing the smooth muscles of the prostate. This is the most commonly recommended group of drugs for men with BPE. Currently, five main types of alpha-blockers are used. They all achieve similar results but differ in their side effects:
Usually, the drugs are fully effective within a couple of weeks, but some men will notice an improvement within hours or days after starting treatment. Alpha blockers do not reduce the size of the prostate or prevent it from growing. Some men will eventually need surgery to relieve their symptoms.
Side effects of alpha-blockers are mild and most men do not experience any side effects, even if they use them for a long time. Men who have side effects report loss of strength (asthenia), dizziness, and slightly lower blood pressure (hypotension).
A few alpha-blockers may also cause dry orgasm also known as ejaculatory dysfunction. This is an uncommon side effect and it will disappear when the treatment is stopped.
Alpha-blockers may affect the muscles in your eyes. This side-effect is not harmful but if you are scheduled to have cataract surgery you should inform your surgeon about the treatment with alpha-blockers.
5alpha-reductase inhibitors (5ARIs) are a group of drugs which prevent the prostate from growing and may even shrink it. These drugs work better in prostates larger than 40 millilitres and are only prescribed when the prostate enlargement causes bothersome symptoms. 5ARIs will improve the symptoms 6 to 12 months after starting treatment. These drugs may reduce the risk of urinary retention and the need for surgery. 5ARIs take a long time to improve the symptoms, so they are only advised for treatment which lasts over a year. 5 alpha reductase inhibitors reduce prostate size with 18 to 28% and decrease the level of PSA with approximately 50% after 6-12 months of treatment.
There are 2 types of 5ARIs, and they achieve similar results:
The side effects of these drugs are mainly related to sexual function. They may include reduced sexual drive, erectile dysfunction, and problems with ejaculation. However, incidence of sexual dysfunction is low in these patients and even decreased with treatment duration. About 1-2% of men experience breast enlargement or nipple tenderness. Side effects are not very common and disappear when the treatment is stopped
5ARIs are generally recommended for men with moderate or severe symptoms because of the possible side effects.
These drugs are most often used in combination with other types of drugs. Possible combinations of drugs are discussed later in this section.
Muscarinic receptor antagonists
Muscarinic receptor antagonists (MRAs) are a group of drugs which reduce the abnormal contractions of the bladder. These drugs are usually prescribed for the treatment of overactive bladder symptoms (OAB). They can also help men with urgency symptoms caused by BPE. They are generally not prescribed if the bladder does not empty completely and there is much urine left in the bladder after urination.
There are several types of MRAs:
- Trospium chloride
Side effects of MRAs are usually mild. They may include dry mouth and eyes, constipation, difficulties urinating, symptoms of the common cold, blurred vision, and dizziness.
Phosphodiesterase 5 inhibitors
Phosphodiesterase 5 inhibitors (PDE5Is) are a group of drugs used for the treatment of erectile dysfunction. These drugs can also improve some symptoms caused by BPE.
There are three types of PDE5Is:
Only tadalafil 5 mg (daily dose) has been approved for the treatment of men with BPE. The cost is usually not covered by insurance companies or national health services.
Men with erectile dysfunction as well as BPE may benefit from treatment with daily use PDE5Is.
PDE5Is can cause side effects such as headache, back pain, dizziness, and indigestion. PDE5Is should not be used in combination with several drugs, including the alpha-blockers doxazosin or terazosin. They should also not be used in men who have specific heart problems. Men who have problems with their blood pressure or who have kidney failure should also not take PDE5Is. If you experience loss of vision when taking PDE5Is, you should go to your doctor.
Make sure to discuss any of your concerns about the side effects or contraindications of PDE5Is with your doctor.
Combination of drugs
Alpha-blockers with 5ARIs
The combination of alpha-blockers with 5ARIs is recommended if:
- The prostate is larger than 40 millilitres (ml)
- PSA values are 1.5 ng/ml or higher
- Your symptoms are severe
- You have slow flow of urine
This combination of drugs is only advised for long-term treatment.
Alpha-blockers with MRAs
The combination of alpha-blockers and MRAs is recommended if:
- You have storage symptoms
- Your symptoms have not improved when taking one drug
Herbal drugs are made of plant extracts. Many types of roots, seeds, pollen, bark, or fruits can be used alone or in combination to make these drugs. The most widely used extracts in herbal drugs are taken from:
- Pumpkin seeds (Cucurbita pepo)
- South African star grass (Hypoxis rooperi)
- Bark of the African plum tree (Pygeum africanum)
- Rye pollen (Secale cereal)
- Berries of the American dwarf palm (Serenoa repens)
- Roots of the stinging nettle (Urtica dioica)
It is not entirely clear how these herbal drugs work to relieve symptoms caused by BPE. It is also not clear how efficient they are. The quality of herbal drugs can vary greatly. Because there are so many herbal drugs available, no specific recommendation about their use can be made. Inform your doctor during consultation if you take any herbal drugs to relieve your symptoms.
Side effects of herbal drugs are mild and many men do not experience any side effects at all. Gastro-intestinal discomfort (for instance bloating or constipation) is the most common complaint.