Drugs compensatory reactions

One more aspect of compensatory reactions is that with repeated use of a given dose of a drug, they are thought to become stronger. You can see that we have the makings of an explanation of tolerance here, one that was made prominent over 30 years ago by two psychologists, Richard Solomon and John Corbit, when they published their opponent process theory of motivation (Solomon Corbit, 1974). 

The steroid-inhibiting properties of metyrapone have also been used in the treatment of Cushing s syndrome, and it remains one of the more effective drugs used to treat this syndrome. However, the compensatory rise in corticotrophin levels in response to falling cortisol levels tends to maintain adrenal activity. This requires that glucocorticoids be administered concomitantly to suppress hypothalamic-pituitary activity. Although metyrapone interferes with lip- and 18-hydroxylation reactions and thereby inhibits aldosterone synthesis, it may not cause mineralocorticoid deficiency because of the compensatory increased production of 11-desoxycorticosterone. 

In general, because the brain fights back against drug effects, withdrawal reactions tend to produce symptoms that are more or less the opposite of the drug s primary effect. That is, when the drug effect is removed, the brain s compensatory mechanisms are unmasked and take over. 

Hydralazine may cause a dose-related, reversible lupus-like syndrome, which is more common in slow acetylators. Lupus-like reactions can usually be avoided by using total daily doses of less than 200 mg. Other hydralazine side effects include dermatitis, drug fever, peripheral neuropathy, hepatitis, and vascular headaches. For these reasons, hydralazine has limited usefulness in the treatment of hypertension. However, it may be useful in patients with severe chronic kidney disease and in kidney failure. Minoxidil is a more potent vasodilator than hydralazine, and the compensatory increases in heart rate, cardiac output, renin release, and sodium retention are more dramatic. Severe sodium and water retention may precipitate congestive heart failure. Minoxidil also causes reversible hyper-... 

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