Module 2: Basic Pharmacology of Controlled Drugs and Substances

Lesson 1

Barbiturates – Precautions

Regular use of a barbiturate can induce tolerance, making increased doses necessary to produce the desired effect. Tolerance develops more quickly to the mood-altering effects than to the effects on the respiratory system. Thus, the margin between an effective dose and a lethal dose gradually narrows. Psychological and physical dependence can occur with regular use. Withdrawal symptoms include restlessness, anxiety, insomnia, delirium, and seizures, and may result in death (Canadian Pharmacists Association, 2014).

Long-term, high-dose use may result in effects similar to chronic intoxication (impaired vision, memory and judgment, and slurred speech), as well as depression or mood swings. Change in liver function may result in faster metabolism of other drugs (Canadian Pharmacists Association, 2014).

Serious toxicity can result when combined with alcohol or other CNS depressants.


  • Canadian Pharmacists Association. (2014). E-Therapeutics. Ottawa: Author.