One disadvantage of ketamine and tiletamine-zolazepam?

• A. Pain on injection
• B. They are completely reversible with naloxone
• C. They have no hepatic or renal concerns
• D. They are inexpensive

Answer: (A)

Pain on injection is a real drawback of both ketamine and tiletamine-zolazepam. The solutions and formulations used for these drugs can be irritating to tissues, and IM injections in particular often cause noticeable discomfort or struggling as the drug takes effect. This injection pain is a practical issue during induction that can complicate handling and timing.

Why the other statements don’t fit: these drugs are not completely reversible with naloxone because naloxone only blocks opioid receptors, and these agents are not opioids (ketamine is an NMDA antagonist and tiletamine-zolazepam combines a dissociative with a benzodiazepine). They do have hepatic and renal considerations since both components are metabolized by the liver and excreted with renal involvement, so there can be prolonged effects in patients with liver or kidney disease. They are not consistently inexpensive—telazol in particular is relatively costly, and while ketamine itself can be inexpensive, the combination product isn’t typically viewed as inexpensive.