Dependence and withdrawal
Drug tolerance develops rapidly in amphetamine abuse (i.e., recreational amphetamine use), so periods of extended abuse require increasingly larger doses of the drug in order to achieve the same effect. According to a Cochrane review on withdrawal in individuals who compulsively use amphetamine and methamphetamine, "when chronic heavy users abruptly discontinue amphetamine use, many report a time-limited withdrawal syndrome that occurs within 24 hours of their last dose." This review noted that withdrawal symptoms in chronic, high-dose users are frequent, occurring in roughly 88% of cases, and persist for 3–4 weeks with a marked "crash" phase occurring during the first week. Amphetamine withdrawal symptoms can include anxiety, drug craving, depressed mood, fatigue, increased appetite, increased movement or decreased movement, lack of motivation, sleeplessness or sleepiness, and lucid dreams. The review indicated that the severity of withdrawal symptoms is positively correlated with the age of the individual and the extent of their dependence. Mild withdrawal symptoms from the discontinuation of amphetamine treatment at therapeutic doses can be avoided by tapering the dose. Overdose
Interactions
Monoamine oxidase inhibitors (MAOIs) taken with amphetamine may result in a hypertensive crisis if taken within two weeks after last use of an MAOI type drug. Inhibitors of enzymes that directly metabolize amphetamine (particularly CYP2D6 and FMO3) will prolong the elimination of amphetamine and increase drug effects. Serotonergic drugs (such as most antidepressants) co-administered with amphetamine increases the risk of serotonin syndrome. Stimulants and antidepressants (sedatives and depressants) may increase (decrease) the drug effects of amphetamine, and vice versa.
Trolamine salicylate (Aspercreme, Aspergel) is an organic compound which is the salt formed between triethanolamine and salicylic acid. It is used as an ingredient in sunscreens, analgesic creams, and cosmetics. The salicylic acid portion contributes to both the sun protection effect (by absorbing UVB radiation) and to the analgesic effect. The triethanolamine neutralizes the acidity of the salicylic acid. One benefit of this topical analgesic is that it has no odor, in contrast to other topical analgesics such as menthol. The US Food and Drug Administration has not reviewed any of the over-the-counter products listed in the Daily Med database that contain trolamine salicylate. Also, the producers of trolamine salicylate products have not provided evidence to the FDA in support of claims that this chemical is directly absorbed through the skin into underlying tissue. Due to health concerns, in 2019 the FDA issued a proposed rule classifying the sunscreen use of trolamine salicylate as "not generally recognized as safe and effective." One study reported that trolamine salicylate does penetrate into, and persist within, underlying muscle tissue. The test subjects used either the trolamine salicylate product or a placebo while engaging in an exercise regimen designed to induce muscle soreness.