Parenteral drug delivery and microbial infection risks
Drug delivery via the parenteral administration route bears many advantages but also the risk of microbial infection. A recent study on the viability of microorganisms in parenteral solutions underlines the significance of strict contamination control during the preparation and administration of the ready-to-administer parenteral products.
Parenteral administration (usually meaning an intravenous injection or infusion) is one of the most effective ways to administer nutrients or drug products such as painkillers or antibiotics to patients. As substances enter the bloodstream directly, while bypassing the protective barriers of the skin and the gastro intestinal tract, it is crucial to avoid any microbial contaminations beforehand.
Unfortunately microbial contamination can never be completely ruled out, which is why a group of pharmaceutical researchers from the Johannes Gutenberg-University of Mainz recently investigated the survival and growth of selected microorganisms in different parenteral preparations.
For their study, recently published in Pharmaceutical Technology in Hospital Pharmacy, the researchers chose three types of bacteria and one type of fungus known for being able to cause potentially life-threatening infections, typically in patients with pre-existing conditions or a weakened immune system such as HIV or cancer patients.
To investigate the viability of these microorganisms and thus the potential infection risk for patients, the researchers injected the microbes in 17 different sterile non-cytotoxic solutions and monitored their growth/proliferation over a period of five days.
Most preparations did not inhibit microbial growth
As expected, each species showed a different capability to survive depending on the type of test solution. Yet, all of them lost viability after a few hours or days in preparations containing vancomycin, an antibiotic, in midazolam, a common sedative, as well as in phenylephrine, a drug being used to increase blood pressure. However, it should be noted that microbial growth inhibition was not always related to the active substance itself but to associated physico-chemical parameters such as pH and osmolality (the concentration of particles dissolved in a fluid).
Ultimately most of the tested preparations showed only insufficient antimicrobial activity, meaning they did not inhibit the growth of the tested organisms. The results of the study thus strongly underline the importance of working under strictly aseptic conditions when preparing parenteral products in order to reduce the risk of contamination to a minimum and to ensure patient safety.
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