Or, better translated, is the new, fancier option really superior?
In many cases, the intravenous option is superior than the oral alternative. Cephalexin, for example, reaches higher serum levels via intravenous administration. The oral versions of morphine and hydromorphone are not equivalent intravenously. So, what about acetaminophen/paracetamol?
It is already well-established (by the manufacturer) the intravenous version of acetaminophen reaches higher peak serum levels, and does so more quickly, than oral versions. This study, however, asks the question from a patient-oriented standpoint – does this actually provide superior pain relief?
The short answer is no. This small study analyzing 87 patients receiving intravenous or oral acetaminophen in a double-blind, double-dummy fashion found no difference in mean change in pain levels at 30 minutes. This is consistent with the limited previous evidence, and reasonably suggests there is no justification for IV use when patients are capable of taking the oral alternative.
Interestingly, this same group recently presented these data in abstract form with 108 patients rather than 87, and using median pain score reduction rather than means. Their abstract results are consistent with these, but the discordant number of analyzed patients is odd.
“Intravenous versus oral paracetamol for acute pain in adults in the emergency department setting: a prospective, double-blind, double-dummy, randomised controlled trial.”
https://www.ncbi.nlm.nih.gov/pubmed/29247042
The response I have gotten when I try to convince people not to use IV tylenol using data like this: “patients like it because it’s IV.” And “there’s a placebo effect from the IV form.” I wasn’t under the impression it was ethical to deliberately prescribe placebos, but there we are.
Perhaps I wouldn’t call it a placebo as much as avoiding a nocebo – if the patient expects they won’t improve with non-IV/IM therapy, they won’t.