A drug formulation chamber for an intravenous administration set is provided. The intravenous administration set includes a container of an IV fluid, a drip chamber, a drug formulation chamber, and an adapter-needle assembly. The drug formulation chamber has a fluid inlet and a fluid outlet for maintaining a flow of IV fluid through the chamber. A portion of the chamber wall is comprised of a material which is permeable to the drug but which prevents convective loss of the IV fluid. A transdermal-type drug delivery device is adhered to the semipermeable/microporous wall portion. Drug is delivered by the delivery device through the wall portion and into the flowing IV fluid. The device delivers drug into the IV fluid at a rate that is independent of the flow rate of IV fluid through the formulation chamber. The rate of drug delivery from the device into the IV fluid is controlled by either the wall portion or a membrane layer in the drug delivery device. A plurality of drug delivery devices may be adhered to the wall portion to deliver a plurality of drugs or to deliver a single drug at a higher dosage rate.