Drug Classification

Chemical Structure

Pharmacological Activity

The classification scheme given below focuses on each compound's main psychotropic effects which in some cases classifies it differently from what might be considered its primary pharmacological effect (i.e., based on therapeutic use). For example, pseudoephedrine is a popular decongestant that has mild stimulatory properties. Pseudoephedrine's  decongestant effect might be considered its primary effect, while its stimulatory effect would be considered a secondary side-effect. However, from a psychopharmacological perspective, pseudoephedrine's stimulatory effect is its primary effect and its decongestant action is a secondary (although therapeutically more useful) effect. Therefore, pseudoephedrine is classified below as a mild stimulant like caffeine and nicotine.
 
 

Abbreviations: ADHD, attention deficit hyperactivity disorder; AIDS, acquired immune deficiency syndrome; CNS, central nervous system; OTC, over-the-counter (nonprescription) medicines.

Drug Class	Primary Effects/Approved Medicinal Uses	Examples
Opiates/Opioids/Narcotic Analgesics	analgesia, cough suppression, antidiarrhea, suppression of opiate withdrawal, sedation; currently used therapeutically for the first four effects	opium, morphine, codeine, heroin  (diacetyl morphine), fentanyl, methadone, meperidine, L-alpha-acetylmethadol (LAAM)
Narcotic/Opiate Antagonists	block the effects of narcotics; used to treat opiate overdose	naloxone, naltrexone
Psychomotor Stimulants	stimulate psychological and sensory-motor functioning; used therapeutically to treat ADHD and narcolepsy, sometimes as an appetite suppressant, occasionally antifatigue, formerly for asthma and for sinsus decongestion	amphetamine, methamphetamine, cocaine, methylphenidate
Other Stimulants	similar to psychomotor stimulants but with much less efficacy; various therapeutic effects including caffeine compounded with aspirin in some OTC pain relievers, ephedrine in OTC asthma medicines, pseudoephedrine in OTC sinus decongestants and OTC appetite suppressants	caffeine, nicotine, ephedrine, pseudoephedrine
Barbiturates	general decrease in CNS arousal/excitability level; used therapeutically for anesthetic, anticonvulsant, sedative, and hypnotic effects	thiopental, secobarbital, pentobarbital, phenobarbital
Minor Tranquilizers	general decrease in CNS arousal/excitability level, but low dose are somewhat selective for anxiety and much less sedative than barbiturates; used therapeutically as anxiolytics, benzodiazepines also as anesthetics and anticonvulsants	includes two subclasses: benzodiazepines (e.g.,. diazepam, chlordiazepoxide, flunitrazepam [Rohypnol]) and muscle relaxants (e.g., meprobamate)
Major Tranquilizers (antipsychotics/neuroleptics)	general sedation at high doses, with selective antipsychotic activity at lower doses; used therapeutically to treat schizophrenia and other major psychotic disorders	haloperidol, pimozide, flupenthixol, chlorpromazine, spiroperidol, clozapine
Antidepressants	no perceptible CNS effects in normals, but effectively alleviate depression in many depressives; used therapeutically to treat depression	includes three subclasses: monoamine oxidase inhibitors (e.g., pargyline), tricyclic antidepressants (e.g., amitriptyline, desmethylimipramine), and selective serotonin reuptake inhibitors (SSRIs: e.g., sertaline)
Antimanic	dampens extreme mood swings in some people; used to treat manic-depressive (bipolar) disorders	lithium
Alcohol	general decrease in CNS arousal/excitability level; no current therapeutic uses, but formerly used as an anesthetic and a sedative	ethyl alcohol (other alcohols have similar actions but are associated with very toxic effects, e.g., methanol)
Volatile Anesthetics	general decrease in CNS arousal/excitability level; used therapeutically for anesthesia	nitrous oxide, halothane, ether
Volatile Solvents	produce feelings of intoxication, can produce hallucinations at high doses; no therapeutics uses (all can cause marked brain damage in moderately low concentrations	toluene, benzene, naphtha
Psychogenics	produce altered states of consciousness; hallucinogenics produce hallucinations sometimes reported as "mystic" experiences; cannabinoids usually produce increased feelings of "well being" and "mellow" intoxication; the "pleasantness" of the states produced by both classes probably depends partially on expectancies; no approved therapeutic uses, but cannabinoids are being increasingly used for their antinausea, anxiolytic, and appetite-stimulating effects in severely ill patients (e.g., AIDS)	includes two subclasses: hallucinogenics (e.g., lysergic acid diethylaminde [LSD], mescaline, psilocybin) and cannabinoids (e.g., marijuana, hashish).
Stimulatory Hallucinogenics (cf. former psychotomimetics)	produce a mixture of psychomotor stimulant and hallucinogenic effects, depending on dose and other factors; no therapeutic uses, except phencyclidine as a veterinary anesthetic	MDMA (ecstasy), phencyclidine (PCP), ketamine (?)

DEA Drug Schedules

• Schedule I substances have a high abuse liability and no approved medical use. These substances are available for investigational purposes only, and the research protocol must be approved by the Food and Drug Administration (FDA) prior to granting a license for handling Schedule I compounds. Drugs are provided by manufactures under federal contract. Pharmacies do not sell these compounds nor can physicians write prescriptions for them. Special record-keeping and storage procedures are required for all Schedule I substances.
• Schedule II-IV substances have decreasing abuse liabilities (II is the highest) and approved medical uses. Physicians are licensed to prescribe these compounds and pharmacies can dispense them, although pharmacies do not stock all of these substances. Schedule II compounds have more stringent record-keeping and storage requirements than do Schedule III and IV substances.
• Schedule V substances have a recognized abuse liability (and approved medical uses) but are generally not regulated (e.g., they are available without prescription). Many of these substances are used in common, over-the-counter medicines. Including compounds on this schedule facilitates state and local regulations deemed appropriate in some jurisdictions (e.g., An individual state may impose restrictions on some substance considered to have an unexpectedly high abuse liability.).

Addiction Liability