text: Meropenem is administered intravenously as an aqueous solution. Meropenem is stored in vials as white crystalline powder (containing meropenem as the trihydrate blended with anhydrous sodium carbonate). For intravenous administration, the powder is dissolved in 5% monobasic potassium phosphate solution, since meropenem is soluble in 5% monobasic potassium phosphate solution and only sparingly soluble in water (). For intravenous bolus administration, injection vials are reconstituted with sterile water for injection. 
  Reconstituted (dissolved) meropenem degrades over time. The degradation may be associated with color change of the solution, typical for a hydrolysis of the amide bond of the β-lactam ring as seen with most β-lactam antibiotics, while particularly for merapenem the color is changing from colorless or pale yellow to vivid yellowish. Upon reconstitution, the merapenem infusion solution, prepared with 0.9% sodium chloride, exhibits both chemical and physical stability for a duration of 3 hours at a temperature up to °C. If refrigerated (°C), the stability extends to 24 hours. However, when the product is reconstituted in a 5% dextrose solution, it is used immediately to ensure its efficacy. The degradation of meropenem in a water-based solution is affected by factors such as pH, temperature, initial concentration, and the specific type of infusion solution used. Meropenem solutions should not be frozen.
  Meropenem is administered every 8 hours.
  Dosing must be adjusted for altered kidney function and for haemofiltration.
  Studies recomment application of meropenem therapeutic drug monitoring for optimal application.
  As with other β-lactams antibiotics, the effectiveness of treatment depends on the amount of time during the dosing interval that the meropenem concentration is above the minimum inhibitory concentration for the bacteria causing the infection. For β-lactams, including meropenem, prolonged intravenous administration is associated with lower mortality than bolus intravenous infusion in persons with whose infections are severe, or caused by bacteria that are less sensitive to meropenem, such as Pseudomonas aeruginosa.
  Meropenem exhibit poor permeability across the gut and low oral bioavailability because of its hydrophilic properties, which inhibit its passive diffusion across the intestinal epithelium. The challenges related to research of oral delivery of meropenem are related to high susceptibility of meropenem to degradation through hydrolysis of the amide bond in the β-lactam ring, even at relatively low temperatures and humidity. This instability can result in the loss of meropenems antibacterial activity. Besides that, neropenem is unstable in the acidic environment of the stomach, leading to extensive degradation and loss of the drug after oral administration. In addition, intestinal efflux (secretory) transport can pump the drug back into the gut: efflux transporters, particularly P-glycoprotein (P-gp), present in the gastrointestinal tract can actively pump meropenem back into the gut lumen, limiting its absorption and reducing oral bioavailability; in the attempts of oral administration bacteria can develop resistance to meropenem by enhancing the active efflux of the antibiotic through efflux transporters, such as the MexAB-OprM tripartite efflux system in Pseudomonas aeruginosa. Thats why meropenem is administered intravenously.
  There is insufficient data regarding the administration of meropenem during breastfeeding. However, it has been observed that, in general, the concentration of this beta-lactam antibiotic in breast milk is relatively low, therefore, beta-lactam antibiotics are not anticipated to induce detrimental effects in infants who are breastfed. Nonetheless, there have been sporadic reports of disturbances in the gastrointestinal flora of the infant, manifesting as diarrhea or oral candidiasis (thrush), associated with the use of beta-lactam antibiotics, however, these potential side effects have not been thoroughly investigated specifically in the context of meropenem use, therefore, the safety profile of meropenem in breastfeeding mothers and their infants is unknown.