Desmopressin (Minurin®)

Welcome back! Today we will discuss another treatment for bedwetting that we use very frequently: desmopressin.

Although I have included the best-known brand name of desmopressin, Minurin®, in the title, I would like to begin by making it clear that I have no financial interest in this company or any other. I have simply used Minurin® in the title because this is the name most people recognise, and to make clear that we are discussing the same medicine rather than a new drug.

With that clarified, I will answer, one by one, the questions that most often arise when desmopressin is prescribed for bedwetting.

In the previous post, we discussed treatment with a bedwetting alarm. You might think one treatment is better than the other; indeed, alarms have a higher resolution rate and, once they work, the effect is permanent. However, comparing the two is like comparing apples and pears. Each is suited to a different type of patient, so what works for one child may not work for another, and vice versa. While an alarm works very well for children with a high waking threshold, who sleep very deeply and are difficult to wake, desmopressin is helpful for children with nocturnal polyuria.

What is nocturnal polyuria? Let us look at it below:

 

What is nocturnal polyuria?

At night, our bodies normally produce a hormone called vasopressin, also known as antidiuretic hormone. It reduces the amount of urine made by the kidneys, so that only an amount that can fit inside the bladder is produced during sleep.

However, some children do not produce enough vasopressin at night. Their bodies therefore make as much urine at night as during the day, or even more! This means they need to get up to pass urine during the night or, if they sleep very deeply, they wet the bed.

This excessive production of urine at night is called nocturnal polyuria: ‘poly’ means much and ‘uria’ refers to urine.

 

What is desmopressin and when is it used?

Desmopressin is a synthetic variant of vasopressin that can be given as tablets which dissolve quickly in the mouth. It is used in children from 6 or 7 years of age whose bedwetting is caused by producing a large amount of urine at night. In these cases, and only these particular cases, treatment is very effective.

 

How should desmopressin be taken?

Usually, one or two tablets are given each night before bed. Treatment may start at the full dose, two tablets each night, and then be gradually withdrawn if effective. Alternatively, it may begin with one tablet and increase to two if the effect is insufficient. The treatment strategy may vary according to medical judgement and each patient’s bladder diaries.

The tablets should not be swallowed; they should be allowed to dissolve in the mouth, which takes just a few seconds. It is also recommended not to eat solid food immediately before or after taking the medicine.

The tablets are given 30 to 60 minutes before bedtime and work for 8 hours. During this time the body produces less urine, returning to normal the following day. To prevent too much fluid from accumulating in the child’s body, it is recommended to drink only a small amount from one hour before the medicine is given. It is also very important to empty the bladder completely just before going to sleep.

 

When do the effects become noticeable?

Minurin® usually starts to work from the first few nights, although only 60-70% of children with bedwetting respond to treatment. This is why it is important to record daytime and night-time urination before treatment, to check whether nocturnal polyuria is present and choose the most suitable treatment. Even when treatment helps, it may not work on 100% of nights.

 

How long should treatment continue?

If the response is good, treatment is usually continued for 3 months and then gradually withdrawn. Stopping suddenly is not a good idea because it does not give the body time to produce vasopressin itself. A very gradual withdrawal is more effective, allowing the body to adapt and progressively start producing the hormone. If symptoms worsen again when Minurin® is withdrawn, a further 3-month course would be indicated before another gradual withdrawal is attempted. Sometimes treatment cannot be withdrawn and has to continue for years until stopping becomes possible.

However, if there is no improvement after 2 weeks, other methods, such as a bedwetting alarm, should be tried. Some children need several attempts with desmopressin, or a combination with other therapies, to resolve bedwetting completely.

Some families use Minurin® only on ‘important nights’, such as school trips, holidays or sleepovers. This is a perfectly valid option, especially if the child only wets the bed occasionally, but an adult must understand the treatment and supervise the child to ensure they do not drink much during the night.

 

Is desmopressin a safe treatment?

Desmopressin is a very safe medicine when the basic advice described above is followed. Nevertheless, treatment must always start under medical supervision, never on your own initiative. Side effects, such as headache, nightmares, vomiting or abdominal pain, are uncommon and disappear when treatment is stopped. If a side effect is suspected, or if the child takes or is about to start another medicine, a specialist should be consulted.

 

That is all for today. I hope this has been useful. In the next post, we will look at the main causes of daytime urinary incontinence in children. Do not miss it!

 

See you soon,

Dr Oriol Martín Solé, paediatric urologist