Nitrofurantoin, an antibacterial agent used in the treatment of urinary tract infections, is commonly prescribed for children and elderly adults who are unable to swallow tablets or capsules. An oral suspension is available in the United States, but only tablets and capsules are commercially available in Canada. As such, Canadian pharmacists must prepare the suspensions extemporaneously.
At the authors’ institution, nitrofurantoin suspension has traditionally been prepared in a methylcellulose vehicle. On the basis of historical procedures, this extemporaneous suspension has been given an expiration date of 8 days. The methylcellulose suspension presents some major problems including labour-intensive preparation, inability of community pharmacists to prepare (for both technical and logistic reasons), short expiration date, and inconvenience to outpatients.
Ora-Sweet sweetening agent and Ora-Plus suspending agent (Paddock Laboratories Inc, Minneapolis, Minnesota) are now commercially available and help to ease product preparation and improve palatability. Although the stability of nitrofurantoin suspensions in other vehicles has been reported, to the authors’ knowledge there is no published information on the stability of nitrofurantoin in the combination vehicle.
This study examined the physical characteristics and chemical stability (defined as maintenance of more than 90% of initial concentration) of extemporaneously prepared oral nitrofurantoin suspensions of 10 mg/mL in a 1:1 mixture of Ora-Sweet and Ora-Plus, stored at 4°C and 25°C throughout a 91-day study period.