Routes of Medication Administration

There are many routes of medication administration (the way that a drug is placed into the body). Based on the specific medication being used, the rate of absorption desired, and the specific site of action (where the medication needs to have an effect) your doctor or pharmacist will instruct you on the route of administration needed for you.

Most drugs are manufactured for a specific route of administration and must be used as directed for safety and efficiency.

In general, two categories of medication administration exist: parenteral and nonparenteral. These two categories also determine whether or not a drug stays in one area of the body (local effect) or absorbed by the vascular system to be distributed to body tissues (systemic effect).

This administration route involves medication that is injected in the body anywhere other than the mouth or alimentary canal (the entire passage along which food passes through the body from mouth to anus. It includes the esophagus, stomach, and intestines).

Generally, parenteral is the most reliable, direct and rapidly absorbed way of administering medications. This is used when more complete and faster absorption of a drug is needed.

 It describes any medication injected into the body via the following routes:

• Intradermal (injecting a drug into the first layers of the skin)
• Subcutaneous (injecting directly into the fatty tissue under the skin)
• Intramuscular (injecting directly into a muscle)
• Intraarterial (injecting a drug directly into an artery)
• Intracardiac (injecting directly into the heart) 
• Intravenous (injecting directly into a vein)
• Intrathecal (injecting into the spinal canal)
• Epidural (injecting into the epidural space of the spinal cord)
• Intraperitoneal (injecting directly into the abdominal cavity)

The speed of absorption varies with parenteral administration, but it is faster than oral administration, which is a nonparenteral route. Some of the disadvantages of using the parenteral route are that there is a slight risk of infection, tissue damage, pain and/or anxiety for some patients.

Nonparenteral is the route that oral medications (pills, capsules, syrups), topical medications (ointments, patches like nitro), and suppositories (vaginal and rectal) are administered. This route includes: 

• Oral (medications are taken by mouth and absorbed into the system through the digestive system. Absorption is slow. Medications that use this option cannot be used if vomiting is occurring.)
• Sublingual (medication is placed under the tongue for absorption by the body)
• Topical (applied directly to a part of the body)
• Transdermal (active ingredients are delivered via the skin for systemic distribution. Examples include transdermal patches)
• Ophthalmic (administered through the eye, usually in the form of drops)
• Otic (administered through the ear)
• Nasal (administered through the nose)
• Rectal (absorbed by the lower digestive tract)
• Vaginal (administered through the vagina)
• Mucosal (medications are delivered through the nose or inhaled and are absorbed through the nasal mucosa or bronchioles, respectively. Vaginal administration of a medication is also considered mucosal.)
• Percutaneous (medications are absorbed directly through the skin into the bloodstream. Some birth control pills and hormone replacements are administered by patches that are absorbed slowly and evenly through the skin, for example.)

The advantage of using these nonparenteral routes is that it is easier and more convenient for most. Unfortunately, if you are nauseated, vomiting, can't swallow, or have intestinal issues, taking medications via the gastrointestinal tract is not recommended.