A Study of Meropenem Standard 30 Minute Infusion Versus Prolonged 3 Hour Infusion in Intensive Care Unit (ICU) Patients

Meropenem is a powerful antibiotic used in intensive care for people who have very serious infections. Meropenem is rapidly removed from the blood by the kidneys and it is very expensive. In very ill patients in intensive care, it is uncertain how best to give this antibiotic. Studies have suggested that a smaller dose given over a longer period of time, results in blood levels of meropenem that are just as good as when a higher dose is given over a shorter period of time. This direct comparison has not been tested in intensive care patients. It is important to know this because if giving a lesser amount more slowly is just as good, then doctors will choose to give meropenem this way. To establish whether this is the case, the investigators plan to conduct an initial (pilot) study in ten intensive care patients at Austin hospital. Adult (age 18 years or older) patients in intensive care who have a serious infection being treated with the antibiotic, meropenem for three days or more will be able to participate in this study. The decision to start meropenem will be made by the intensive care doctors and they will give it in the usual way for 24 hours. The investigators will then in a random way (like tossing of a coin), give the participant meropenem either in the usual way (1 gram infused over 30 minutes) or give them a smaller amount, but over a longer period of time (500 milligrams infused over 3 hours). This will be done for 24 hours. They will then receive meropenem in the alternative way for another 24 hours. After this time the intensive care doctors will decide how meropenem will continue to be given. Blood levels of meropenem will be measured to see if they are the same when meropenem is given in each of the two different ways. During each different way of giving meropenem, 7 blood samples will need to be taken. Ten mls (or one spoonful) of blood will be required for each measurement. Blood levels will be taken through monitoring lines, which will be alrea