If you have been diagnosed with a (suspected) brain tumour, you are likely to be started on some drug treatments including dexamethasone and often phenytoin.
Dexamethasone is a steroid drug that has proven benefit in reducing the swelling (oedema) caused by some brain tumours. Swelling associated with brain tumours may contribute to the symptoms produced by the tumour including headaches and neurological deficits (weakness, loss of speech, etc.). Steroids should, therefore, help to relieve some of these symptoms.
Dexamethasone normally takes 8-24 hours for the first effects to be apparent.
You will often be prescribed a high dose initially (4mg 4 times per day) and this will be reduced following your treatment, as directed by your treating doctors. Depending on your tumour type and your needs for other treatment (e.g. radiotherapy) you may be advised to remain on a small dose. If you have been taking dexamethasone for more than a few days it is very important not to stop it suddenly, rather the dose should be gradually reduced over a period of days.
Every drug has side effects. The more common side effects with dexamethasone are gastritis or stomach ulcers (to prevent this you will be given an anti-acid drug), increased appetite, weight gain, muscle weakness, diabetes, increased risk of infection, and psychological disturbances. Generally the side effects are worse with higher doses given for longer periods of time.
Phenytoin is an anti-epileptic drug used to treat (or reduce the risk of you suffering) seizures (fits). It is sometimes known by the trade name 'epanutin'. Although it is the most common drug used by neurosurgeons for seizures, some patients are given alternative drugs such as carbamazepine ('tegretol') or valproate ('epilim').
This depends on how the first doses are given and how much you are given. For most rapid effect (e.g. if you have a fit) it will be given intravenously (into a vein) at high dose followed by a regular lower maintenance dose, commonly 300mg per day, which is often taken as 1 tablet at night. However, phenytoin needs to be given at a precise dose in order for it to work and too much can cause side effects - this will be checked by blood tests intermittently to check the levels in your bloodstream.
Your blood levels will determine how much you need to take in the long term. If you have been suffering seizures, you may need to stay on medication in the long term (as directed by your doctors). If you have received phenytoin only as a measure to prevent seizures (e.g. around the time of surgery), and you have never suffered a seizure, it is likely that your doctors will recommend a short course only. If you have been on phenytoin for a long time (weeks or longer) and it is decided to stop the drug, it should be withdrawn slowly over a few weeks.
Like all drugs, phenytoin has side effects. If taken at too high a dose, it may cause nausea, vomiting, tremor, insomnia, unsteadiness, slurred speech and blurred vision. Even if you are on the correct dose other side effects occasionally occur, including rashes, gum thickening, fevers, hepatitis, swollen lymph nodes and disorders of blood cells. Sometimes you will need to stop the drug or change to another drug if you develop severe side effects (as directed by your doctor). If you think you have developed a side effect then you should report this to your doctor (GP or surgeon) as very rarely some of the side effects can be life threatening.