Tragically, more widespread availability of prescription opiates, such as hydrocodone and oxycodone, has fueled an epidemic of opioid abuse that surpasses that associated with heroin. In 2014, it was estimated that 4.3 million Americans engaged in non-medical use of prescription opioids, and that prescription opioid overdoses led to approximately 19,000 deaths, mainly from respiratory failure. Moreover, an increasing number of heroin users start with prescription opioids, then switch to heroin because it is a substantially less expensive habit. This trend underlies a near doubling of heroin use in the United States between 2005 and 2012. Current efforts are focused on making opioid antagonists widely available to first responders, which has prevented many deaths, and tightening the use of prescription opioids to limit their potential for abuse.
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Marijuana, or “pot,” is the most widely used illegal drug. As of 2014 in the United States, 22.2 million people (7.0% of the population) admitted use during the previous month. Several states in the United States have legalized the “recreational” use of marijuana, and more states appear poised to follow; thus, its status as an illicit drug is undergoing reevaluation.
Marijuana is made from the leaves of the Cannabis sativa plant, which contain the psychoactive substance Δ9tetrahydrocannabinol (THC). When marijuana is smoked, about 5% to 10% of the THC content is absorbed. Despite numerous studies, whether the drug includes persistent adverse physical and functional effects remains unresolved. Some of the untoward anecdotal effects may be allergic or idiosyncratic reactions or are possibly related to contaminants in the preparations, rather than to marijuana’s pharmacologic effects. On the other hand, beneficial effects of THC include its capacity to decrease intraocular pressure in glaucoma and to combat intractable nausea secondary to cancer chemotherapy.
The functional and organic CNS consequences of marijuana have received great scrutiny. Marijuana use is well recognized to distort sensory perception and impair motor coordination, but these acute effects generally clear in 4 to 5 hours. With continued use, these changes may progress to cognitive and psychomotor impairments, such as the inability to judge time, speed, and distance. Among adolescents, such impairment often leads to automobile accidents. Marijuana increases the heart rate and sometimes blood pressure and it may cause angina in a person with coronary artery disease.
The lungs are affected by chronic marijuana smoking; laryngitis, pharyngitis, bronchitis, cough, hoarseness, and asthmalike symptoms all have been described, along with mild but significant airway obstruction. Smoking a marijuana cigarette, compared with a tobacco cigarette, is associated with a 3-fold increase in the amount of tar inhaled and retained in the lungs, as a consequence of deeper inhalation and longer breath holding.