Desmopressin: Two doses a day keeps the urine away!
I was shocked and disappointed to recently discover that there was a national shortage of desmopressin acetate, a medication commonly used to treat diabetes insipidus (DI). After undergoing transsphenoidal surgery to remove a pituitary tumor this year, pathology revealed that the offending mass had damaged part of my pituitary gland. As a result, I was diagnosed with DI and prescribed desmopressin therapy to manage my symptoms.
What is diabetes insipidus?
Although there is more than one type of DI, for the purpose of this blog post, I am referring specifically to CENTRAL diabetes insipidus, which can result from a head injury, infection, tumor or neurosurgery. DI is a relatively uncommon condition where the patient’s body is unable to retain enough water. This can result in excessive thirst and frequent urination, which is very diluted and pale or colorless instead of being the usual yellow, and does not reduce in volume even if the patient decreases fluid intake. DI symptoms can also include nocturia (the need to get up from sleep at night in order to urinate). Indeed, before being given desmopressin therapy, I often visited the bathroom about three or four times every night…. Certainly not something that is conducive to a good night’s sleep, which is necessary to aid the recovery process. Another one of my symptoms included a strong craving for icy cold water and I literally drank liters of water faster than I could chill it (thank goodness for the bags of ice cubes kept in the freezer). Although the word “diabetes” generally refers to diabetes mellitus (“sugar diabetes”), diabetes insipidus is not specifically related, although both conditions are characterized by extreme thirst and polyuria (excretion of considerable quantities of urine). For this reason, it is sometimes called “water diabetes”.
Some science behind diabetes insipidus
DI generally occurs because of a deficiency of an important antidiuretic hormone called vasopressin (also known as ADH), which is responsible for controlling the release of urine from the kidneys. Vasopressin is made by the hypothalamus in the brain and is stored by the pituitary gland (the master gland of the endocrine system). When the amount of water in the body becomes too low, ADH is released from the pituitary gland – This helps to maintain water by instructing the kidneys to produce less urine (and to instead return water into the bloodstream). When there is insufficient vasopressin, the kidneys are unable to properly conserve water whilst they carry out their function of filtering blood, and too much fluid gets passed from the body in the form of diluted urine. A shortage of vasopressin is usually caused from damage to the hypothalamus or the posterior (back part) of the pituitary gland. |
The good news
The good news is that DI can usually be managed effectively with the synthetic antidiuretic hormone replacement therapy of vasopressin (desmopressin, DDAVP), which may be taken in nasal spray (intranasal), tablet (pill), or intravenous (injection) form. The manufactured version of ADH works similarly to natural ADH in your body by preventing the kidneys from producing urine when the level of water in the body is low. When treated, DI does not cause any major problems or reduced life expectancy. However, if fluids aren’t replaced DI can cause severe dehydration and other serious conditions (especially in children, the elderly or in those who have other complicating health issues). It is therefore, important to have your electrolytes monitored to ensure that you are on the correct dose of medication and to carry an adequate supply with you when you are away from home. I have also read on many medical websites that it would be pertinent to wear a medical alert ID bracelet or necklace to inform caregivers of your condition in an emergency situation.
I was prescribed the tablet form of DDAVP, although some patients prefer the nasal spray because it can be more quickly absorbed into the bloodstream. The spray, however, may not be suitable for some patients, such as those who have recently undergone transsphenoidal or sinus surgery, or for those who have a cold, as the nasal passages will likely be congested or blocked. In some cases, patients may switch to the intravenous method (e.g., those who have poor intranasal absorption or because they are undergoing surgery). Since taking desmopressin, my DI symptoms have improved dramatically and I no longer need to lug a large flask of water around with me, as if it were an oxygen tank. I am also able to enjoy a good night’s sleep and don’t seem to experience any significant or bothersome side effects (although I must admit that it is difficult to isolate some of the side effects from some other conditions and medications that I am currently encountering).
The bad news
The bad news is that there currently appears to be a national shortage of the drug desmopressin. The U.S. Food and Drug Administration (FDA) recently announced that such a shortage was due to increased demand and manufacturing delays (See here for more information). Although this shortage is said to specifically relate to the intravenous (IV) form, a few patients also seem to be having trouble obtaining other types of the drug. I contacted my own pharmacy and the person I spoke to appeared oblivious to any shortages. However, I’m not overly confident in the information (or lack thereof) provided by this particular individual. Despite the fact that he had said he was a qualified pharmacist, he’d never actually heard of the medication desmopressin and was unresponsive when I asked if he would check with their supplier for availability of the drug. I did, however, directly contact Ferring Pharmaceuticals who said that desmopressin vials were indeed on back order, although the nasal spray was still available (Ferring do not have any dealings with the tablet form).
Summary
Diabetes insipidus can be a serious medical condition and often needs to be treated with desmopressin therapy. It is important that you see your general physician if you think you may have DI. He or she will ask you about your symptoms and carry out the appropriate tests (which should include the water retention test) or refer you to an endocrinologist for further examination. If you have already been diagnosed with DI and are having problems obtaining your medication, you may find it helpful to contact your own pharmacy for additional information. The Pituitary Network Association (PNA) are advocating on behalf of DI patients who are unable to obtain desmopressin and request that those in difficulty contact them accordingly (See PNA link below for more instructions).
Sources/links
I Had Brain Surgery, What's Your Excuse? by Suzy Becker
