Researchers Identify Need for Palatable Compounded Metronidazole Suspension

With metronidazole commonly used to treat infections, such as C. difficile, in neonates and pediatric patients, pharmacists and pharmacy technicians can use a non-aqueous vehicle and certain sweeteners to improve palatability for these patients in order to ensure that they are medication adherent, according to an abstract at the American Society of Health-System Pharmacists 2021 Midyear Clinical Meeting.

Metronidazole is not commercially available as an oral suspension, so the compounded suspension for young patients is commonly prepared with metronidazole benzoate powder; however, this suspension has been on back-order for more than a year. When prepared with the commercial tablets or base API powder, the suspension is extremely bitter and is commonly refused by pediatric patients.

To investigate options that might make the suspension more palatable for this population, researchers reviewed and evaluated published compounding and stability information and prepared sample suspensions. According to the abstract, all of the formulations prepared with the commercial tablets or base API powder were unpalatable.

Additionally, different flavoring and sweetening agents known to mask bitter tastes were added to the suspensions, but all failed. The study authors noted that when bitter substances are dissolved in aqueous bases, the bitterness is exposed to the entire mouth and is easily detected. However, non-aqueous vehicles will coat the drug particles in a suspension, allowing the oil to act as a barrier between the drug and the patient’s taste bud receptors.

Several non-aqueous vehicles are commercially available, although they are not well known, with a fixed-oil suspension also available for compounding. Additionally, sweetening agents such as stevia and vanilla are also known to mask bitter tastes.

Using this knowledge, the researchers developed a compounded metronidazole suspension formulation using a non-aqueous vehicle and a commercial masking agent. This sample compound was found to be a palatable suspension for both adult and pediatric patients, and current official USP standards were used to determine a beyond-use date of 6 months.

Based on these findings, the researchers said the new compounded non-aqueous metronidazole suspension is being used. Most patients are tolerating it thanks to the improved taste and because it is not as viscous as the former metronidazole benzoate oral suspension. Because it has a long beyond-use date, the suspension can be unit-dose packaged and kept for immediate use in the inpatient setting and would be easy to store for the outpatient setting as well.

REFERENCE

(Management Case Study) Developing a Palatable Compounded Metronidazole Suspension. Abstract. American Society of Health-System Pharmacists 2021 Midyear Clinical Meeting. Accessed December 7, 2021. https://www.eventscribe.net/2021/midyear/agenda.asp?pfp=OnDemandSchedule