Drugs or foods competing for enzymes in the liver, or damage to the liver itself, can delay the metabolism of a drug so that the drug stays at a high level for a long time. Kidney damage can also raise the level of drug in the blood. Both the time of day the drug is taken and whether it is taken on a full or empty stomach can change the amount and rate of absorption as well. Drugs are metabolized at different rates in different people; a small dose may be as effective in some people as a large dose in others. This variation depends not only on obvious differences, such as weight and height, but also on age, race and sex. In the past, most dosages were calculated for the average-size white male. In 1993, legislation was introduced in the United States so that the drug trials run by pharmaceutical companies before the drug was marketed had to consider dosages for females as well. Blood tests during these trials measure the level of drug in the blood, allowing for further fine-tuning.
All the cells of the body use NTs to conduct information, not just those in the brain. Therefore, medications affecting the level of NTs may also affect the stomach, the muscles, the urinary tract, the sex organs, the eyes, and many other systems. Some of the side effects are minor and fairly predictable; even if they make you uncomfortable, you need not stop the drug. These side effects are not dangerous and they usually diminish in a week or so. But if you develop a more serious reaction, such as a skin rash, severe infection, jaundice, or a marked decrease in urination, you should stop the drug and call your doctor, or go to the A & E department of your local hospital, right away.
Do not stop these medications because you feel a bit better and think you don’t need them anymore. If you stop them for even a few days, the changes in the cells will stop and you will have to start the process all over again. Since it can take four to eight weeks to get the medication’s full effect, this will be very discouraging. Studies show that only about 60 per cent of people end up properly taking the drugs they are prescribed, for either medical or psychiatric illnesses.
For example, Dorothy was prescribed paroxetine for severe, debilitating depression. She took it for three weeks, but stopped taking the medication a week before her appointment with the therapist because she hadn’t noticed any improvement. She was alarmed by darting electric shock-like feelings in her head. As soon as she restarted the paroxetine, these disappeared; they had been a withdrawal reaction to the abrupt stopping of paroxetine. Her doctor gradually reduced the dose over a three-week period, so she wouldn’t have withdrawal effects. Since the paroxetine had not been effective for Dorothy, she started on another antidepressant, and her depression lifted over the next three weeks.
If the drugs are working, you will first notice an improvement in sleeping and eating, and then a sense of calm, so that you are less upset by stresses. After about four weeks you will notice your mood improve. At first, be cautious about activities that require alertness and coordination. If you like a glass of wine when you go out with friends, it’s probably best to forgo it when you first start the medication. It’s also probably safer not to drive until you are familiar with the effects of the drug. If you are very agitated or unable to sleep, your doctor may prescribe a mild tranquilizer or sleeping pill until the antidepressant takes effect.
Millie came to see her doctor complaining of a ten-pound (5-kg) weight loss, early-morning wakening, agitation, fatigue, difficulty concentrating, and guilty feelings about an abortion she had had twenty years previously that she couldn’t stop thinking about. She felt that life was not worth living, but had no plans to kill herself. She had been depressed and listless for about a month. Her doctor diagnosed a major depression and chose to start her on venlafaxine at a dose of 75 mg daily.
Within four days, Millie called saying she was more agitated and didn’t feel she could continue on the medication. She had also thrown up a couple of times. The doctor suggested that she continue the medication but take the dose on a full stomach after her supper. When she returned to the clinic for her next appointment, she said she was feeling a bit less frightened and was sleeping longer. Her appetite had returned and she had not lost any more weight. She was told to increase the dose to 150 mg daily. Three weeks later, she reported that she was beginning to feel more like her old self.
If you don’t feel any better after about six to eight weeks, then another drug, usually from the same group, can be tried. If there is some change but not as much as you would like, the antidepressant effect can sometimes be increased by adding an augmenting drug such as lithium, tryptophan – an amino acid that metabolizes (is converted) into the NT serotonin – or the hormone thyroxin. Your doctor can also prescribe antidepressants from two different groups at the same time, or a ‘dual-action’ drug that fits into more than one group.
Note that you will not develop tolerance or addiction to antidepressants. You will gradually feel better, but not ‘high’. If you do feel elated on antidepressants, you may be developing hypomania (bipolar II, or ‘soft’ bipolar disorder), or mania, and the addition of a mood stabilizer will help.