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SINGAPORE - A drug used to enhance erectile function can now also be prescribed to combat the lower urinary tract symptoms related to an enlarged prostate.
They include a frequent or urgent need to urinate, a weak urine stream, a sense of incomplete relief and dribbling of urine at the end.
With the drug, tadalafil, which goes by the trade name Cialis and is manufactured by Eli Lilly, patients with benign prostatic hyperplasia need take the 5mg pill only once a day.
Previously, they had to pop several pills and run the risk of side effects that affected sexual function.
Both these reasons made patients unwilling to stick to the treatment, said Dr Colin Teo, the head and consultant at the department of urology at Khoo Teck Puat Hospital.
He thinks they will find tadalafil, which has been used to treat erectile dysfunction since 2003, more appealing.
The drug received approval from the Health Sciences Authority for this second purpose in January this year.
It is now used in four public hospitals and about 60 private clinics for treating both erectile dysfunction and signs and symptoms of benign prostatic hyperplasia.
Checks with three urologists showed that they have put more than 50 men who suffer from both conditions on tadalafil.
What ails ageing men
It is common for men to have both erectile dysfunction and benign prostatic hyperplasia as they age.
Erectile dysfunction is an inability to develop or sustain an erection and affects one in five men here, said Dr Lewis Liew, a urologist at Gleneagles Medical Centre and Mount Elizabeth Novena Hospital.
It is a problem that rises with age, as blood flow to the penis is affected by medical conditions such as diabetes and heart problems and the use of certain medication, among other factors.
Approximately half of those aged 60 and above here have erectile dysfunction, Dr Liew added.
Likewise, the prostate - a walnut-sized gland that is part of the male reproductive system that produces semen - can become enlarged in older men, leading to a condition called benign prostatic hyperplasia.
Dr Li Man Kay, a urologist and kidney transplant surgeon at Gleneagles Medical Centre, said 80per cent of men with prostate enlargement also have erectile dysfunction.
Side effects from medicine
Side effects from medicine
The drugs used to treat benign prostatic hyperplasia come in two classes - alpha blockers and 5-alpha reductase inhibitors - and both can have an impact on sexual function.
Alpha blockers relax the muscle of the prostate and bladder neck to relieve lower urinary tract symptoms, while 5-alpha reductase inhibitors slow the growth of the prostate and may even shrink it.
Patients with a larger prostate may be on both types of medication.
Dr Lee Fang Jann, a consultant at the department of urology at Singapore General Hospital, said 3 to 8 per cent of patients on alpha blockers may suffer dizziness, sudden drops in blood pressure from changes in body posture and body weakness.
Dr Li added that between 10 and 15 per cent of patients also have retrograde ejaculation, that is, semen is ejaculated backwards into the bladder instead of out through the penis.
Dr Lee said that 5 to 9 per cent of patients using 5-alpha reductase inhibitors also have side effects of decreased libido and erectile dysfunction.
Tadalafil has no such side effects.
In a European study of 511 men aged 45 and above, who had lower urinary tract symptoms suggestive of an enlarged prostate for more than six months, tadalafil was shown to be as effective as an alpha blocker in reducing those symptoms.
The study, which was published in January last year in European Urology, the official journal of the European Association of Urology, also found that tadalafil significantly improved erectile dysfunction compared with a placebo, while alpha blocker tamsulosin did not.
The most common side effects of tadalafil were headache, followed by nasopharyngitis (infection of the upper respiratory system), back pain, dizziness and dyspepsia (gastric pain).
The action that makes tadalafil - and other drugs that treat erectile dysfunction such as sildenafil (Viagra) and vardenafil (Levitra) - improve erectile function is the same one that also improves symptoms of prostate enlargement.
By blocking the phosphodiesterase-5 (PDE-5) enzyme found in blood vessel walls, these drugs help the smooth muscles of the penis to relax and increase blood flow.
Hence, these drugs are called PDE-5 inhibitors.
The PDE-5 enzyme is also found in the prostate and bladder, so taking tadalafil helps to increase blood flow to both these organs and control lower urinary tract symptoms.
Tadalafil does not affect the size of the prostate, so a patient with a large prostate who is taking tadalafil may still require 5-alpha reductase inhibitors.
How the drug works
How the drug works
While it is welcome news to patients that they can have one drug that treats two conditions, not everyone will be able to afford tadalafil, which costs about $200 for a month's supply.
In comparison, alpha blockers cost about $30 and 5-alpha reductase inhibitors about $100 every month, Dr Li said.
He said in making a decision if a patient should use tadalafil or older drugs, he takes into account his frequency of sex, financial ability and sexual expectation.
Even then, men who take nitrate drugs for angina (chest pain) cannot take tadalafil, as both types of medication can interact to cause their blood pressure to drop so low that they may suffer a heart attack.
A 58-year-old retiree, who declined to be named, told Mind Your Body that tadalafil has improved both his prostate symptoms and sex life.
He used to have to urinate almost every hour in the day and four or five times at night.
He recalled: "I had a 'high-tide' feeling all the time, but in the toilet, there was a weak urine stream."
He was diagnosed with prostate enlargement late last year by Dr Liew and put on an alpha blocker, which helped to reduce his urinary frequency.
But he was put on tadalafil in February this year after Dr Liew learnt he also had erectile dysfunction.
The retiree regards this as his "miracle drug" now.
He admitted shyly that even his wife has noticed the difference during sex.
It also helps that he no longer wakes up at night to use the toilet so he gets a good night's sleep.
He said: "I'm confident of myself as a man and feel like what I did in my 20s and 30s."
joanchew@sph.com.sg
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