Question

A drug delivery catheter consists of a cylindrical needle whose wall contains very small pores allowing the drug solution to leave the needle into the surrounding tissue. The hydraulic conductance of the needle wall is 10−5 cm2 s g−1. The needle has a length of 2 cm and the diameter of the needle is 200 μm. The sharp end of the needle is closed off so that any flow of drug solution into the needle must flow out through the porous wall of the needle. The drug solution has a viscosity of 1 cP. If the pressure driving the drug solution into the needle is 5 mmHg, how long will it take in seconds for this catheter to deliver 100 μL of the drug solution into the surrounding tissue? Assume that the pressure is constant at 5 mmHg (gauge) within the 2 cm length of the needle and that the pressure in the surrounding tissue is 0 mmHg (gauge). Also assume that the pores in the needle wall are of such a size that no solutes are retained

Answer 1