Module 2: Basic Pharmacology of Controlled Drugs and Substances

Lesson 1

Opioids – Pharmacodynamics  (cont’d)

Physical dependence is a characteristic response to the use of this class of drugs, and is manifested by withdrawal symptoms when therapy is discontinued. In general, the severity of withdrawal symptoms depends on the specific drug, the dose of the drug and duration of therapy (short-term or chronic).

Typical signs and symptoms of withdrawal include:

mild hypertension tachycardia tachypnea
anxiety restlessness agitation
nausea vomiting diarrhea
yawning lacrimation rhinorrhea
mydriasis diaphoresis piloerection
muscle spasms pain


(Canadian Pharmacists Association, 2014; NOUGG, 2017).

Acute withdrawal symptoms reach their peak after about 36-72 hours and are usually over within 7 to 10 days, but it may be 6 months or longer before total recovery from withdrawal occurs. Along with physical dependence, tolerance to the effects of opioids should also be anticipated. This occurs quite rapidly, usually within a few days, for side effects such as sedation, respiratory depression, euphoria, and emesis (Canadian Pharmacists Association, 2014).