Ampicillin & Gentamicin

[gayle omansky]

When we use Ampicillin & Gentamicin for intravenous therapy it has been our habit to dose with the Ampicillin first because it is readily available in the unit, then start the Gentamicin dose second. The discussion at the moment is whether the Gentamicin should be first and how much of a wait between the two medications. Would you all share your thoughts.

Thanks, Gayle

[Karen]

Hi Gayle

In our unit, we start with Ampicillin and 2nd Gentamicin. We give Ampicillin over a slow IV bolus of 5 minutes, and then Gent is given over 30 minutes. At one time we waited 30minutes between medications, however, our pharmacist at the time determined through research, that as long as there was a good flush between medications, that the Gent could be given immediately following the Ampicillin. To my knowledge, we have not run into any difficulties managing in this way.

[Ruth]

That has been my experience aswell. We dont choose one over the other to go 1st but ensure that the line is flushed between each drug to ensure there is no mixing

[nungabrielia]

It has also been our practice in the NICU to give Amp. first over 5 minutes...flush well and give Gent. over 30 minutes. as per our pharmacy in the unit. we also have not had any side effects...

Sister Gabrielia

NICU RNC

LONG BEACH MEMORIAL MED CENTER...CA, USA

[Guest pscheans]

The inactivation of aminoglycosides by penicillins has been reported in in vitro studies, but not so much in in vivo. Here is the abstract of some evidence to support not separating the dosing...

Pat Scheans, MS, NNP-BC

Legacy Health

Portland, OR

Daly JS, Dodge RA, Glew RH, Keroack MA, Bednarek FJ, Whalen M. (1997). Effect of time and temperature on inactivation of aminoglycosides by ampicillin at neonatal dosages. J Perinatol. Jan-Feb;17(1):42-5.

The administration of gentamicin at least 1 hour before administration of ampicillin in neonates has been advocated because of in vitro inactivation of aminoglycosides by beta-lactam antibiotics. This method would cause a delay in ampicillin dosing in the treatment of serious bacterial infections and unnecessarily complicate nursing procedures. We studied the effect of varying concentrations of ampicillin (50, 100, 200, and 400 micrograms/ml) on aminoglycosidic antibiotics in vitro with the use of stock solutions diluted in pooled sera obtained from cord blood and incubated samples at 25 degrees C, 37 degrees C, and 40 degrees C. We found inactivation of aminoglycosides to be dependent on time, temperature, and ampicillin concentration, but the degree of inactivation was small and does not support temporal separation of parenteral administration of ampicillin and aminoglycosides to neonates.

[gayle omansky]

Thank you everyone for taking the time to answer this question. It is reassuring that our practice is in line. Particular thanks for the citation - we will get this article.

Gayle

[Guest Mohammed]

in our unit we recommend giving ampicillin first we dilute 500 mg vial in 5 cm distilled water then we give the calculated dose .

gent. is then given soon after after dilution 10 mg in 1 cm distilled water . we find no problem in this regimen

[ph-adil]

When we use Ampicillin & Gentamicin for intravenous therapy it has been our habit to dose with the Ampicillin first because it is readily available in the unit, then start the Gentamicin dose second. The discussion at the moment is whether the Gentamicin should be first and how much of a wait between the two medications. Would you all share your thoughts.

Thanks, Gayle

In our unit we started any one of them as long we are flashing the line before administering the second agent.

For the new admission the are using their floor stock to start the dose then a after all the iv preparation should be prepared and send from pharmacy.

Usually they make the ampicillin final concentration 100mg/ml then according to that they calculate the dose following neofax guidline. For gentamycin the final concentration is to be 4mg/ml for the first dose.

The rest of the doses we prepare in pharmacy. For stability reason we prepared less concentrated i mean 50mg/ml for ampicillin and 2 mg/ml for gentamycin.

For gentamycin as it is concentration dependent we give the total dose once daily and peck and trough level to be obtained 30 mins pre and post administration of the third dose.

For ampicillin as it is time dependent we give the total dose in divided dose and over 30 mins.

[gayle omansky]

Hi Adil,

Thank you for responding to my question. It is interesting that your facility uses a less concentrated preparation of the medications. Can I ask you why you administer Ampicillin over 30 mins? Often it is given over 5 or 10 mins.

Regards, Gayle