Barbiturates including phenobarb suppress the medullary respiratory center to induce respiratory depression. Patients with underlying chronic obstructive pulmonary disease are more susceptible to respiratory depression even at doses that are ordinarily therapeutic in healthy individuals.
Barbiturates also suppresses the medullary vasomotor center to cause depression of cardiovascular tone and contractility which is associated with hypotension and reduced cardiac output. Individuals with congestive heart failure are more vulnerable to these cardiovascular effects.
Phenobarbitone when co-ingested with other CNS depressants such as alcohol, opiates, or benzodiazepines, the net effect is an additive depressant effect on the CNS and respiratory system.
The . . .
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