ExCPT Pharmacy Technician Practice Exam 2026 – Complete Prep Resource

Phenobarbital is classified as a controlled substance because it is a barbiturate, which is known for its potential to cause dependence and abuse. The classification of a drug as controlled is based on its potential for addiction and how it is regulated under the Controlled Substances Act. As a barbiturate, phenobarbital is used primarily as a sedative and anticonvulsant, which makes it subject to strict regulations to prevent misuse. The other drugs listed, while they may have therapeutic benefits, do not fall into the same category of concern for dependency and abuse as phenobarbital does. Carbamazepine is classified as an anticonvulsant medication but is not a controlled substance; it is instead generally considered safe and effective for conditions like epilepsy and bipolar disorder. Imipramine, an antidepressant, is also not regulated as a controlled substance despite having potential side effects. Furosemide, a diuretic, is not associated with abuse potential and therefore is not classified under controlled substances.