Intravenous administration (IV)

Drugs may be given into a peripheral vein over a few minutes or longer by infusion. If given as a single injection the plasma concentrations over time often look like those shown in the graphic. Rapid injections are used to treat epileptic seizures, acute asthma, or cardiac arrhythmias.



  • A quick response is possible (it takes 1 min to circulate and 10-15 seconds to get to brain). Plasma concentration can be precisely controlled using IV infusion administration.
  • The whole dose is delivered to the blood stream. This means that the bioavailability is considered to be 100% after IV administration. Larger doses may be given by IV infusion over an extended time. Poorly soluble drugs may be given in a larger volume over an extended time period.
  • Irritant drugs can be given via a central line in order to be quickly diluted and decrease local damage.



  • It may be difficult to find a suitable vein (or insert central line). There may be some tissue damage at the site of injection.
  • Because the full dose is instantly administered followed by a rapid response, toxicity can be a problem with rapid drug administrations. For drugs where this is a particular problem the dose should be given as an infusion, monitoring for toxicity.
  • Trained personnel are required to give intravenous injections.
  • Sterility, pyrogen testing and larger volume of solvent means greater cost for preparation, transport and storage.