Different kinds of drugs are given in different ways. Many drugs work the same way by altering the cell activities once in the body.

Entrance into the body

Many drugs are given orally. They may be given in other ways. They may be inhaled, injected, or applied to the skin. There is another kind of drug that must be inhaled to produce unconsciousness and that is an Anesthetic gas. It is easy and safe to swallow a drug when taking it to relieve a pain. Some drugs cannot be taken exactly like the others because stomach juices may destroy them. The body may be quickly cured when given an injected drug. Injection may be painful and it prevents risk of infection. The transdermal patch is a device that is attached to the skin like a bandage and it has a layer of medication. The drug that seeps through the skin to the bloodstream may be released by the patch. An Implantable is the other device that has a metal disk with a chamber that can be filled by injection.
 
 

Many drugs that are taken in the form of inhaling, swallowing or injecting, enter the blood stream and travel throughout the body. These drugs pass from the blood into the cells mof the tissues where the drug action occurs. Eye drops, local anesthetics and nasal sprays are the other kinds of drugs that act before entering the blood stream. The amount is too small to produce additional effects on the cells when they enter the blood. The effects of drugs may be created by altering cell activities.

Pharmacologists developed the receptor theory that can tell apart the chemical reactions in every living cell controlling the cell's activities and this theory also tells how drugsn act on cells. They act on a cell by altering one or more of these chemical reactions. These chemical reactions are not only one process between the body and a drug. Drug metabolism is the changing of drugs and is one way in which the body protects itself against drugs. Many of these drug metabolisms occur in the liver. A drug can be changed into a weaker substance longer by a diseased liver. As a result, physicians reduce drug dosage for a patient with liver disease.

Effect on the body

All drugs can affect the body in harmful and helpful ways. A particular drug may produce a stronger heartbeat, relief from pain, or some otherdesired effect. Undesired effects can be caused by the other drugs especially if they are overdosed. Many drugs produce changes throughout the body and this is because the drugs ciculate through the blood stream. As a result, many of these drugs used to affect one part of the body also affect other parts. At some times physicians prescribe morphine to relieve pain. This morphine may also alter the activities of cells in the brain and that reduce the feelingg of pain. It also alters the function of cells in the body that are not involved in feeling the pain. It can create other undesired effects, cause vomiting and it may decrease the rate of breathing.

The effects of the drugs are strengthened as the dose is increased. They are also weakened as the dose is decreased. During the dose of a drug most of the people do not react the same way to a change. If drugs are overdosed, it may triple the strength of the drug effects in one person and not increase the effects in someone else. There can be three kinds of harmful reactions that a drug can produce and those reactions are Side reaction, Hypersensitivity reactions and Toxic reactions.

Side reactions are also  called side effects and they occur with all drugs. A physician can foretell these reactions and be able to tell a patient  wahat to expect. Most of the harmful effects of morphine are side reactions and should be expected. Many drugs may cause side reactions that do not prevent the use of the drug. Hypersensitivity reactions are also called llergic reactions and they occur in people who are allergic to a particular drug. Some of these reactions are forceful and some of them are less important. People who are easily hurt to a particular drug may be allergic to such reactions. Some people are allergic to common drugs such as asprins or penicilin and they cannot take them to release pains. Toxis reaction result from drug poisoning. Some of its reactions may damage cells and kill a person. All drugs have a mild toxic effect and a large overdosed drug will produce an intense toxic reaction.

Drug dependence

People who always take large amounts of drugs such as amphetamines, alcohol, barbiturates, or narcotics may become dependant on the drugs. They have a very strong physical need for a drug's effect. The person who is using the drugs must take large doses to get the desired effects. The development of physical dependence is called Drug addiction. An intense withdrawal sickness occurs if a person stops taking the drug.

Elimination from the body

The body removes drugs with other waste materials. Many drugs travel from the cells through the bloodstream to the kidneys and are eliminated in the urine. The body also removes drugs in tears, sweet and solid wastes. Some of the anesthetics are eliminated when in exhaled breath.
 

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