Final answer:
The statement that phenothiazine tranquilizers frequently cause vomiting is incorrect. These drugs, including acepromazine, actually possess antiemetic properties, which prevent vomiting.
Step-by-step explanation:
Phenothiazine tranquilizers such as acepromazine are frequently used as anesthetic agents. Analyzing the statements given in relation to these drugs, one option does not accurately describe the effects or properties of phenothiazines: They frequently cause vomiting. This statement is incorrect because phenothiazines are known to have antiemetic effects, which means they help to prevent vomiting.
In contrast, it is true that they are synergistic with opioids, can cause hypotension, and importantly, they are not analgesics. This means they do not relieve pain, instead, they produce sedation and have calming effects.