To investigate whether the injectable formulation of methotrexate (MTX) given as an easily prepared oral solution of MTX diluted in water results in serum concentrations similar to those obtained with MTX tablets; to describe an easy and safe method of dispensing the drug.
Six patients (5 women, 1 man) with rheumatoid arthritis were given 10 mg of liquid MTX orally. The liquid was prepared by diluting 0.4 ml of the injectable formulation of MTX (50 mg/2 ml) in 8 ounces of water. One to 2 weeks later these patients were given 10 mg of MTX in the tablet form. MTX serum concentrations were determined using a fluorescence polarization immunoassay. The area under the concentration vs time curve (AUC), maximum concentration (Cmax) and the time to reach maximum concentration (tmax) were determined from the resulting concentration vs time curves.
There was no statistical difference in the variables measured (AUC, Cmax, tmax), demonstrating comparable concentrations with these 2 methods of MTX administration. Patients found the medication easy to administer, potential hazards with the use of needles were avoided, and the cost of the drug was greatly decreased.
The administrator of this easily prepared MTX solution is an alternative to the conventional administration of MTX tables, and may be of particular benefit in patients with financial limitations.