Drug injection is a method of introducing a drug into the body with a hollow needle and a syringe which is pierced through the skin into the body (usually intravenous, but also intramuscular or subcutaneous). It often applies to substance dependence and recreational drug use. This act is often colloquially referred to as "slamming", "shooting [up]", "banging", "pinning", or "jacking-up", often depending on the specific drug subculture in which the term is used (i.e. heroin, cocaine, methamphetamine).Although there are various methods of taking drugs, injection is favoured by some users as the full effects of the drug are experienced very quickly, typically in five to ten seconds. It also bypasses first-pass metabolism in the liver, resulting in a higher bioavailability for many drugs than oral ingestion would (so users get a stronger effect from the same amount of the drug). This shorter, more intense high can lead to a dependency—both physical and psychological—developing more quickly than with other methods of taking drugs. As of 2004[update], there were 13.2 million people worldwide who used injection drugs, of which 22% are from developed countries.