Pfizer Limited makes Caverject, a brand of alprostadil, states EMC. The individual injects the medicine into the side of the penis with a small needle prior to attempting intercourse, according to WebMD. The individuals should not inject the medicine into visible veins, notes EMC.
Injected medication for erectile dysfunction works by relaxing the muscles around the penis, which relieves pressure on the blood vessels in the penis and facilitates increased blood flow. Erections induced by injected medication last 30 minutes or longer, and the duration is commensurate with the amount of medication taken, according to WebMD. Doctors prescribe injected erectile dysfunction medication for both psychological and physiological causes.