Illicit Drugs

Some chemical substances are dangerous to health due to their addictive nature, impact on the central nervous system metabolism, life-threatening side effects, and associate behavioral and mood changes. Drugs classified by the U.S. Drug Enforcement Administration (DEA) under Schedule I are considered illicit drugs when sold to or consumed by the public, except for some chemical derivatives with restricted and controlled medical applications. These are also known as psychoactive drugs of abuse, due to their effects in mood, sensory perception, and behavior. Substances of the following classes are considered illicit drugs: opiates, hallucinogens, depressants, and stimulants under Schedule I (tightly regulated use and supply), as well as the controlled substances under Schedules II, III, IV, and V, when used or sold without medical prescription. Among the most common illicit drugs in use are:

cannabinoids (such as marijuana and hashish oil)
hallucinogens (LSD, mescaline, peyote, MDMA)
dissociative anesthetics (PCP, ketamine, dextromethorphan)
stimulants (amphetamines, methamphetamine, cocaine)
depressants (GHB, rohypnol, barbiturates, benzodiazepines)
narcotics (opium, heroin, methadone, codeine)
inhalants (nitrous compounds, glues, solvents, ether).

Drugs of abuse affect the brain structures that regulate feelings of reward, personal empowerment, and pleasure, which constitute an important component of their addictive properties, along with developed tolerance.

The initial effects of cannabinoids, such as relaxation, euphoria, and diminished concentration, are similar to alcohol. The active chemical of cannabinoids (the alkaloid THC or tetrahydrocannabiol) apparently interferes with nerve cells access to glucose (an essential source of energy for brain metabolism and function), inducing an aftermath sensation of acute hunger. Addiction is followed by increased tolerance, which leads to more frequent consumption and/or to increased doses. The speed of signal transfer between nerve cells (synapses) is reduced with long-term use, as a consequence of the loss of neurons (nerve cells) and components of nerve cells. Poor memory, learning difficulties, and a general apathy are the results of prolonged, frequent use of cannabinoids. Respiratory complications are also common, because cannabinoids are usually inhaled through smoking. High levels of THC in the brain may induce toxic psychosis and hallucinations, especially when the leaves are consumed in foods or infusions. In food or drinks, marijuana effects take about one hour to begin and last for approximately four hours. Flashbacks sometimes occur in some individuals in the three days following a high-dose intake.

Hallucinogens such as LSD, MDMA, mescaline, psilocybin, psilocin, and muscimol are drugs that interfere with neuronal pathways that process sensory information, and also affect the metabolism and levels of chemical messengers known as neurotransmitters, such as serotonin and dopamine. Hallucinogenic plants such as psilocybin, and peyote cactus, along with psilocin mushrooms have been taken by tribal medicine men in search of "visions" for centuries. Hallucinations are altered states of sensory perception that lead to all kinds of pleasant or unpleasant sensory experiences. They affect several functional brain structures that control emotions, behavior, body temperature, cardiac rate, blood pressure, sensory-motor coordination, and breathing. LSD (lysergic acid diethylamide) is a strong hallucinogen with unpredictable effects that may last for approximately 12 hours and create frequent occurrences of flashbacks in the following two days. However, it is not an addictive drug and most users stop using it over time. LSD induces tolerance in frequent users, however, leading to ingesting increased amounts of the drug. The results could include long-lasting mood disorders, psychotic episodes, severe depression, and suicide. These adverse effects may persist for years after the individual has stopped LSD consumption, suggestive of some forms of brain damage.

Mescaline is extracted from the peyote cactus, and also induces hallucinations along with physiologic changes similar to those caused by LSD. Effects last between 8 and 12 hours and its metabolites are detectable in urine for two or three days after use. Hallucinogenic mushrooms such as Psilocybe cubensis and Amanita muscaria, are highly toxic for liver and kidney cells. They induce drowsiness alternating with psychomotor agitation, distorted auditory and visual sensory perceptions, and lack of concentration, as well as nausea, paranoia, and chronic mental disorders.

MDMA, or ecstasy, is both a hallucinogen and a stimulant drug that dramatically increases the levels of serotonin in the brain, causing a sensation of immense joy, amplification of tactile sensations, altered body temperature, and increased sexual drive. MDMA interference with the metabolism of the neurotransmitter serotonin results in nerve cell toxicity that may cause brain damage. Cases of coma and death are also reported in association with MDMA. Frequent use of ecstasy has also indirectly influenced the spread of sexually transmitted diseases including HIV because of its ability to decrease sexual inhibitions and its frequent use in nightclubs.

Dissociative anesthetic drugs were first developed as pharmaceutical products for sedation or for general anesthesia. Dextromethorphan is a sedative of certain autonomous brain functions. Ketamine and PCP (or phencyclidine) are drugs for general anesthesia that present side effects of auditory and visual distortion, and sensations of "floating" above the environment or above oneself (out-of-body sensation). These two substances block glutamate pain receptors in the brain. The neurotransmitter glutamate is responsible for signaling pain sensation, and is also involved in memory formation, the learning process, and mood modulation. PCP inhibits dopamine, serotonin, and norepinephrine reuptake from cell receptors. These neurotransmitters control the modulation of feelings of reward, joy, euphoria, and physical energy. Phencyclidine is also a dissociative drug of potential abuse that induces dissociative anesthesia, a state in which the patient is conscious without feeling pain. In surgical centers, physicians carefully monitor the vital signals of a patient under PCP, ketamine, or other CNS depressant anesthetics, due to their dangerous and sometimes unpredictable side effects on blood pressure, elevation of body temperature, and heartbeat. When these drugs are illegally taken, users frequently end up in emergency rooms with convulsions, coma, hyperthermia (high core body temperature), or cardiac arrest. Addicts also undergo mood disorders, such as violent behavior, hallucination, panic episodes, paranoia, disorientation, memory loss, depression, and suicidal tendencies.

Depressant drugs, such as flunitrazepam (e.g., rohypnol) and gamma-hydroxibutyrate (or GHB) are frequently mixed with alcoholic beverages, a combination that is sometimes lethal. Rohypnol, often called the "date rape" drug, belongs to the family of benzodiazepines, drugs introduced in medical practice to control anxiety and nervousness. Because rohypnol markedly depresses the central nervous system (CNS), slows motor reflexes, causes disorientation and temporary amnesia, it is used by some who mix the drug in their victim's drink. As the drug is tasteless, odorless, and colorless, sexual assailants use it in nightclubs and parties, without the knowledge of their targets. GHB is now an illegal anabolic drug that was largely used by body builders between 1980 and 1992, when its use became forbidden in the United States. It has a sedative and euphoric effect, may induce coma, convulsions, breathing difficulties and vomiting, especially when mixed with alcohol or cannabinoids.

Stimulants affect the brain reward centers, inducing sensations of euphoria, boldness, and aggressiveness because they accelerate basal metabolism, cardiac rate, and increase blood pressure and sensory motor response. They also cause dizziness, insomnia, behavioral and emotional disorders, sexual inhibition, and lack of concentration. Cocaine is a strong stimulant and highly addictive drug that is trafficked in two chemical forms, hydrochloride salt (powdered cocaine), and freebase form (or crack). Powdered cocaine is inhaled into the nasal passages or diluted in water and intravenously injected, whereas crack is smoked. Cocaine and crack affect the dopamine pathways by attaching to the molecule that transports dopamine to cellular receptors, preventing dopamine reuptake from receptors. Therefore, it prolongs the effects of dopamine in the brain. Both forms of cocaine induce tolerance, leading to increased doses and more frequent consumption. Irritability, mood swings, restlessness, auditory hallucination, and violent behavior develop and tend to worsen through long-term cocaine abuse. Cardiac arrest or coma is a common cause of death when these and other stimulants are mixed with other drugs or alcohol, or taken in high doses.

Narcotics are chemical derivatives from opium, such as codeine, morphine, and heroin, with very effective analgesic activity in relieving intense pain. However, because of their highly addictive properties and some dangerous adverse effects, a total of 23 opium derivatives are classified under Schedule I. Morphine is the most powerful analgesic found in natural opium, but both natural and synthetic opioid compounds are effective intense-pain inhibitors. Morphine causes analgesia without inducing loss of consciousness, along with a sense of wellbeing. Normal doses of morphine and other opioids depress the brain centers that regulate breathing by diminishing their sensitivity. With doses progressively higher, respiratory depression occurs, thus leading to death from acute overdose, a common result of opioid abuse. Other effects of chronic use of opioids are low blood pressure (hypotension), vomiting, constipation, and depression. Repeated use induces tolerance to the respiratory centers as well as decreased analgesia and euphoria, leading to dependency of higher doses and more frequent use, which increases the risk of accidental overdose.

Inhalants are chemical vapors derived from substances and solvents used in glues, wax, and domestic household products, as well as nitrous compounds and ether. They usually either depress the CNS or block oxygen access to the brain. Inhalants are often the first drugs that children experiment with. A study by the National Institute on Drug Abuse (NIDA) of 2003, named "Monitoring the Future," has shown that 12.7% of 10th graders and 11.2% of 12th graders had used inhalants at least once.