Final answer:
A concern when taking barbiturates, benzodiazepines, and barbiturate-like drugs is respiratory depression.
Step-by-step explanation:
When taking barbiturates, benzodiazepines, and barbiturate-like drugs, one concern is respiratory depression. These drugs are central nervous system depressants, and they can suppress the activity of the respiratory system, causing slow and shallow breathing. This can be potentially dangerous, especially if taken in overdose or combined with other CNS depressants like alcohol or opiates.