Unlike central nervous system (CNS) depressants, stimulants increase breathing, heart rate, blood pressure, and alertness - and can create euphoria and decrease inhibitions.
Prescribed stimulants include methylphenidate (Ritalin® and Concerta®) and amphetamines (Adderall® and Dexedrine®).
While these stimulants may be prescribed for a variety of health conditions (1). For this section, we will only describe the effects of commonly used unprescribed substances - including caffeine, cocaine, amphetamines, and methampethamines.
Pharmacology is a branch of science that deals with the study of drugs and their actions on living systems - that is, the study of how drugs work in the body.
Stimulants may be prescribed for a variety of health conditions (1). For this section, we will only describe the effects of commonly used unprescribed substances.
Common unprescribed stimulants in pregnancy are caffeine, cocaine, and amphetamines.
Stimulants act by augmenting the action of catecholamines, either by increasing release, inhibiting reuptake, or both.
Effects of stimulants are increased breathing, heart rate, blood pressure, alertness, euphoria, dilated pupils, vasoconstriction, decreased inhibitions and anorexia.
Side effects can occur with normal or higher than normal doses and include palpitations, paranoia, restlessness, seizures, or decreased attention.
There is insufficient evidence to support tolerance with prolonged use.
Half-life varies depending on the substance; half-life for cocaine is 1 hour; caffeine is about 5 hours; most amphetamines are about 12 hours.
Stimulants are metabolized in the liver, and then eliminated via urine, with elimination times depending on urine pH (1).
How does caffeine keep us awake?
"Over 100,000 metric tons of caffeine are consumed around the world every year. That’s equivalent to the weight of 14 Eiffel Towers! Caffeine helps us feel alert, focused, and energetic, even if we haven’t had enough sleep — but it can also raise our blood pressure and make us feel anxious. So how does it keep us awake? Hanan Qasim shares the science behind the world’s most widely used drug."
There are no pharmacological treatments for dependence on stimulants, although there is emerging data about a few promising medications (2). Individual or group therapy may be helpful when there is a desire to change patterns of stimulant use (3).
Similar to trends for other illicit substance use in pregnancy, people who use stimulants tend to decrease their use over the course of the pregnancy, which dramatically decreases risks (4, 5).
The Food and Drug administration places methamphetamine, cocaine and caffeine in pregnancy category C (1).
Stimulants have not been linked to congenital anomalies or placental previa (6, 7, 3, 9, 8, 4, 10, 11).
Stimulants may lower birth weights and gestational age at delivery, increasing the risk of small for gestational age (SGA) or low birth weight (LBW) and accompanying morbidity (3, 7, 45, 12, 13, 14, 8, 15).
Many studies find that these differences disappear when controlled for confounding factors related to socioeconomic status and access to prenatal care (16, 17), or that findings of decreased birth weight, while statistically significant, are still within normal range (4).
The evidence for a causal link with cocaine to placental abruption is of very poor quality and does not adequately control for confounding factors (18-24).
There is no evidence based neonatal withdrawal from stimulants.
Stimulants are present in the breastmilk of parents who use them, and infant exposure should be limited (25-27).
Abstinence from stimulants during lactation is recommended, but in the case of a relapse, waiting at least 24 hours after cocaine use and 48 hours after methamphetamine use to provide human milk is recommended (26, 28).
Low to moderate caffeine use is considered safe during pregnancy and breastfeeding, but high doses could result in lower birth weights and spontaneous abortion (27, 29, 30-32).
There is no evidence of increased risk of congenital anomalies with caffeine use. Safe doses during pregnancy and lactation are likely to be around 200 mg/day (30).
Stimulants are present in the breastmilk of parents who use them, and infant exposure should be limited (25-27).
Overdose from stimulants does not directly cause death. Deaths involving stimulants are usually related to vascular events such as myocardial infarction, cerebrovascular accident, or aneurism (33).
Caffeine withdrawal involves headaches, irritability, sleepiness, and constipation (34).
There is evidence for acute abstinence, or “crash”, from illicit stimulants. The crash from cocaine is usually reported to last 1-2 days and the crash from methamphetamine is reported to last 7-10 days.
Symptoms consistently reported in the literature are anhedonia, irritability, anxiety and paranoia, malaise, insomnia or hypersomnia, anorexia or hyperphagia, fatigue, and psychomotor retardation or agitation.
Similar to the subjective feeling of hangover experienced after heavy alcohol use, this crash is generally mild and does not require medical intervention.
It is not comparable to the predictable, measurable withdrawal syndrome demonstrated by chronic alcohol, benzodiazepine, and opioid use.
However, that it is not medically dangerous does not mean that it is clinically insignificant. As one researcher put it, “There continues to be considerable uncertainty about whether amphetamines (in this review, amphetamine, dextroamphetamine, and methamphetamine) should be regarded as having a true withdrawal syndrome (i.e., a predictable set of symptoms which are reliably found across users).
Nonetheless, many users report symptoms which are clinically severe in that they may lead to subjective distress, premature termination of treatment, relapse to further drug use, and suicidal ideation and attempts.” (35).
There is no evidence for long term physiological withdrawal (36-45).
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