Drug Interactions Two or more drugs present in the body at the same time may interact with each other.

Independent The drug does its job without one affecting the performance of the other. (No interaction) example: taking amoxicillin to kill the bacteria causing an ear infection and Tylenol to relieve pain caused by the ear infection. This is almost always the aim of the prescribing doctor.

Antagonistic One drug opposes the action of another drug = 1 example: some antibiotics block the action of the hormone ingredients of birth control pills.

One drug is doubled in its action when taken with another drug = 2 example: aspirin taken along with a blood thinner, such as coumadin, may be the same as taking a double dose of coumadin.

One drug is more than doubled in its action when in the presence of another drug = 3 example: drinking an alcoholic beverage and then taking an antihistamine may triple the action of the antihistamine and cause unconsciousness or even death.

Drug Entry Routes Drug Entry Routes In order for a psychoactive drug to get to the brain, it must first enter the bloodstream.

The drug enters into the bloodstream primarily through the wall of the small intestine by being swallowed either in a liquid or solid form An example would be amoxicillin tablets, alcohol, Tylenol, etc.

The drug enters the bloodstream by way of a needle being inserted into a vein (IV) muscle (IM), or fat. Vaccines are usually administered by IM and insulin shots are usually administered through fat. Morphine and heroin are usually IV.

The drug enters the bloodstream by way of the alveoli in the lungs. This is the quickest way for a drug to reach the heart and brain. Examples are nitrous oxide, ammonia, and ether or other substance not intended for medical use, like paints, markers, aerosols, etc.

The drug enters into the bloodstream through the skin or mucus membranes. An example would be a transdermal patch, dip, cocaine, suppositories,etc.