Remifentanil NEW

J. Gagnon, Kate Elliott March '08

Page Index:

Introduction/Indications
Description of the Drug
Manufacturer's Package Insert
Administration
Pharmacy Notes

Introduction/ Indications

In the next few weeks remifentanil will be available in the OR pyxis for use in the main OR. At this point we anticipate using remifentanil only in cases where its unique pharmacokinetics will be useful—specifically 
  • neuro cases using SSEP, MEP
  • intra-op wake up tests (ortho, spine)
  • craniotomies and perhaps
  • Carotid Endarterectomies, as well as other cases that are quite stimulating and then have little or no pain afterward such as 
  • suspension laryngoscopies.

Due to the presence of glycine in the formulation, Remifentanil is contraindicated for epidural or intrathecal administration.

Description

Remifentanil is a mu-agonist opioid that is roughly equipotent to fentanyl but equilibrates with the brain more rapidly (like alfentanil).

It contains a structurally unique ester linkage and is hydrolyzed by nonspecific esterases to non-active metabolites. Remi's unique, rapid metabolism and low volume of distribution yields a drug that is rapidly titratable, noncumulative and has a rapid complete recovery. Bolus doses reach peak effect within several minutes and infusions reach equilibrium in about ten minutes. The rate of decline of plasma concentration is nearly independent of the duration of infusion—the context sensitive half time is 4 minutes is constant regardless of the length of the infusion. Remifentanil's opioid effect will vanish in approx 5-10 minutes after the infusion is stopped. 

The duration of action of the drug is not prolonged with renal or hepatic failure, but it is prolonged somewhat by mild hypothermia.
Does not release histamine.

Side effects are typical of mu opioids; chest wall rigidity, bradycardia and hypotension, respiratory depression and nausea and vomiting. These issues will respond to standard treatments.

A unique problem with the use of remifentanil is inadequate analgesia after cessation of the drug; this medication will wear off quickly and completely. An alternate, adequate method of analgesia must be started near the time that remifentanil is discontinued. There is some element of acute opioid tolerance that develops during remifentanil infusions. This can make postop pain management challenging.

Manufacturer's Package Insert

The complete manufacturer's Package Insert, current as of August 2006, is available for downloading in  pdf format by clicking here.

Administration

Mixing remifentanil is easy, on the back of both the MAC and GA SmartLabel plates the directions for mixing are present.

We have remifentanil Smartlabels for our Baxter InfusOR pumps (the ones we use for propofol). Currently only labels for the GA dose range are available.

 Typical doses are 0.2-0.5 mcg/kg/min. Bolus doses (1 mcg/kg, administered over 30-60") can be used prior to GA and result in predictable apnea, bradycardia, and hypotension so be ready! 

Pediatric induction doses of 1 mcg/kg have been associated with bradycardia and hypotension so consider a smaller dose. Obviously bolus dosing is not a good idea for MAC cases-- at this point I think we should limit remifentanil to GA cases only.

As already mentioned remifentanil is perfect for cases that are stimulating during the case but not very painful after. CEAs, neuro. Also great for cranis, SSEP and MEP monitoring cases provides a steady level of analgesia that can be shut off rapidly to assess the patient. It takes about 7-11 minutes. For GA big back cases some will use it with propofol drip alone or with propofol and less than 0.5 MAC of an agent, of course no paralytic is used in these cases. Generally starting at 0.125 then titrating just as any other narcotic to whatever is required I have never gone above 0.7 and generally I am in the range of 0.25 to 0.5.

Another way to use it is with general TIVA cases with LMAs or ETTs.  A second infusion of propofol is used at 100-200 mcg/kg/min.. This is good for a GA case where the surgeon is VERY good at local for postop pain and the patient has PONV issues or fasttrack is desired for an outpatient. Inguinal hernias, breast biopsies, lumpectomies, etc. Some see this technique as the future for outpatient anesthesia eliminating vapor and decreasing PONV and PACU stay time. One thing about this technique is when the patientt is waking up they will often look like they are coming around eyes open etc BE CAREFUL they may still be apneic. Sometimes it seems that the propofol is gone and the remifentanil is still there. You need to really make sure their respirations are adequate prior to removing LMA or ETT.

Do not transfer extubated patients on remifentanil infusions to PACU or SCU. The nursing staff is not familiar with the drug and the potential for accidental respiratory depression exists in an extubated patient.

Pharmacy

Remifentanil is available in the MMC Pyxis, currently just in 1mg vials, which must be mixed and diluted. The manufacturer also supplies it in 2mg and 5mg vials, but we are not stocking these.

Currently remifentanil costs approx $10/mg, (about enough for a one hour case in an adult). Please be mindful of the expense and use this drug only in a situation in which it is specifically indicated.

Return excess drug as you do now, fitting a 60 cc syringe into a brown envelope may require a little tape to secure things. Lastly please check the box "other" under analgesics on the QA form.