8(b)Dexamethasone
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A person with a brain tumour will be prescribed, promptly after diagnosis and in preparation for an operation, the corticosteroid drug dexamethasone ('dex', for short).
This is a steroidal anti-inflammatory. Our bodies naturally produce a substance called cortisol, in a daily amount approximately equal to 0.7mg of dexamethasone. Dex is about five time stronger than the anti-inflammatory drug prednisone, which in turn is about five times stronger than hydrocortisone.
There is no substitute for this drug available. It is not a cure, it does not stop the tumour. Its role is to oppose inflammation and swelling, as discussed in the preceding section. This grants time and comfort for the patient. Also, by reducing pressure, it allows the brain to tolerate radiotherapy or chemotherapy treatments that also cause inflammation.
The good value of dex is reduction or elimination of the symptoms... these vary from person to person depending on where the tumour is. If you have a resurgence of symptoms, it may be that this can be managed, quality of life sustained, by increasing the dex. Otherwise, if symptoms are gone or down, you try to get the dex dose lowered — gently.
As an anti-inflammatory, dex also opposes wound healing — wound healing is closely associated with the inflammation reaction. There is thus a particular concern in its use around neurosurgery — it will be appropriate to get the dex dose up to reduce swelling before the operation, then a concern to get it down, to allow healing, after the operation.
While dex is similar to the natural bodily hormone cortisol, its administration — in doses way above normal daily human needs — has some deranging effects. This means that while it is invaluable in tumour management, every effort is made to minimise the dose, or wean the patient right off dex, if possible. Here are some of the side effects:
• in a very small percentage of patients, there is a susceptibility to corticosteroid psychosis. This is not always recognised by doctors, on the basis of anecdotal information, the experience of patients associated with our group. If a person taking dex begins to behave very strangely, it may be the drug, not necessarily the person's brain, impacted by the tumour... This is a very important issue to address with doctors if this problem arises. . According to literature, steroid psychosis is generally not something that creeps up, but according to experience of some of our members, it can indeed develop over time. It will be manifest in emotional disturbance or anger or in delusional states, the sufferer believing that some very unreal things are happening. Doctors are not in the habit of warning about this, but it seems important for both the person taking this medicine and the carer, to be aware that this could happen. Better to know that the drug could be doing such a thing than to feel wounded psychologically by sudden, deviant, out-of-character behaviour;
• raging appetite and weight gain. Lots of people experience this;
• bone and muscle wasting. Elevated corticosteroid doses cause an excess of catabolism, the process by which mineral resources are drawn daily from our muscles and bones, as we do work. If this is sustained, as in long term use of dex, the result is a weakening and reduction of muscle and bone, particularly in the upper legs and arms. Over time, this may give rise to a risk of injury, especially in the context of weight gain;
• other hormonal disturbance. There is a natural cycle of steroidal hormonal production and management, and this disturbance in level in corticosteroids impacts on that balance. There may be a loss of energy and other symptoms as in hypothyroidism or Chronic Fatigue Syndrome. If these symptoms are severe, a thyroid check may be desirable;
• as part of the hormonal disturbance, problems of sugar management may arise, and a person may develop diabetes. Increase thirst and very frequent urination are the most common common symptoms of diabetes onset, and if these symptoms should develop, please talk to the doctor.
When a person is given supplements of corticosteroid drugs, including dex, our regulatory systems reduce or shut down our natural production of cortisol. This means that if a person weans off the dex, the adrenals may need some encouragement to be kicked back into action. For this reason, there is a need to proceed with weaning with care through that normal level of human production, around 0.7mg a day. A common practice is not to try to make the dose smaller and smaller then but to alternate days of dose at 0.5mg with days without dose. The half life of dex (the period within which the level of the chemical in the body reduces by one half) is about 35 hours, so doses two day apart will send alarm bells ringing to get things going again. Extremes of fatigue may be experienced; rest to accommodate that, it's worth getting off the drug... if it is not needed to keep symptoms at bay.
It is important not to abandon taking dex suddenly if a patient is doing well. Too-sudden dose reductions can cause a big surge in inflammation, swelling and pressure, and a rapid return of symptoms. By the same token, when a patient is at a terminal stage of illness, weaning of dex may be inappropriate, there may be a time when swift withdrawal has virtue (see later section).
In advance of an operation, a surgeon may prescribe perhaps 16mg dex a day, in four daily doses of 4mg [4mg qid]. After the operation, the dose may swiftly drop to 8mg then 4mg, to promote healing, as discussed above. If there is a return of symptoms, the dose may need to go up again. But in general, the ambition is always to lower the dose. The longer the dose has been high, the longer the wean must take. Easy to go to 16mg then back to 4mg in several days, but if a patient has been at say 8mg for weeks, dose reductions need to be very gradual, a schedule of many weeks to get back to zero, even though tumour may be stable or gone from scans. A mild increase in symptoms may not mean a need to make a shift to sustained higher dose. A day or so of bigger dose may knock the swelling problem and allow the earlier lower dose to be maintained. This is a matter for medical management; it will help the doctor to have from you clear advice on whether symptoms are rising or abating at any dose, or in response to dose change. Work with the doctor on this. Give her or him the information to allow good choices of dose. And don't allow the real desire to get off the drug to prevent you from reporting symptoms from which you could be protected with a little more dex. The issue, in fighting a ferocious enemy, is to win days of quality of life, to steal every moment possible from the tumour.
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