ROUTES OF DRUG ADMINISTRATION

DEFINITION
• Routes of Administration is the path by which the drug, fluids or any chemical substances are taken in to the body for producing a target effect on those substances.

The various routes of drug Administration
• Enteral
• Parenteral/ Injection
• Topical
• Sublingual/ Buccal
• Rectal
• Vaginal
• Ocular
• Otic
• Nasal
• Inhalation/ Nebulization
• Transdermal

Enteral Route
• Enteral Route are those medications that are administered through the Gastro Intestinal tract and enter directly to the Intestines.
• Many drugs can be administered orally as liquids, capsules, tablets, or chewable tablets. The oral route is often used as it is the most convenient and usually the safest and least
expensive.
• Drugs administered orally, absorption may begin in the mouth and stomach. However, most drugs are usually absorbed from the small intestine. The drug passes through the intestinal wall and travels to the liver before being transported via the bloodstream to its target site.
• The intestinal wall and liver chemically alter (metabolize) many drugs, decreasing the amount of drug reaching the bloodstream.

Parenteral/ Injection Route
• The parenteral route is any route that is not enteral (par- besides+ enteral- Intestines).
• Parenteral administration can be performed by injection, that is, using a needle and a syringe, or by the insertion of an indwelling catheter.
• Drugs administered through Injection have rapid action. And certain drugs are also made in such a way to prolong drug absorption from Injection site for hours to days and therefore those products are injected in long Intervals.

Intradermal Injection
• It is a shallow or superficial injection of a substance into the dermis, which is located between the epidermis and the hypodermis.
• It is used for skin testing some allergens, and also for mantoux test for tuberculosis.

Subcutaneous (Under the Skin)
• The needle is inserted into fatty tissue just beneath the skin. After a drug is injected, it then moves into small blood vessels (capillaries) and is carried away by the bloodstream.
• Protein drugs that is large in size like Insulin is administered in this site.

Intra Muscular (into the Muscles)

• It is preferred route when larger volumes of a drug product are to be administered. Because the muscles lie below the skin and fatty tissues, a longer needle is used to administer the Injection.
• Drugs are usually injected into the muscle of the upper arm, thigh, or the gluteal region.

Intra Venous (Into a vein)
• Intravenous administration is the best way to deliver a precise dose quickly and in a well-controlled manner throughout the body. It is also used for irritating solutions,
which would cause pain and damage tissues if given by subcutaneous or intramuscular injection.
• A solution containing the drug may be given in a single dose or by continuous infusion.

Intra thecal Route (into the Spinal Canal)
• A needle is inserted between two vertebrae in the lower spine and into the space around the spinal cord & the drug is then injected into the spinal canal.
• This route is used when a drug is needed to produce rapid or local effects on the brain, spinal cord, or the layers of tissue covering them (meninges)—for example, to treat infections of the CNS. Anesthetics and analgesics (such as morphine) are sometimes given through this route.

Intra Arterial (into an artery)

• Intra-arterial drug injection or infusion is a method of delivering a drug directly into artery or arteries to localize its effect to a particular organ/body region.
• It is used in rare conditions on emergency situations. Vasodilator drugs & thrombolytic drugs are administered in this route.

Intra osseous (into the bone marrow)

• It is an indirect intravenous access because the bone marrow drains directly into the venous system. This route is occasionally used for drugs and fluids in emergency medicine and pediatrics when intravenous access is difficult.

Intra Articular (into the Joint Space)
• A hypodermic needle is injected into the affected joint where a dose of anti- inflammatory agents like corticosteroids are administered usually to treat Osteoarthritis and relief from joint pain. Intra Peritoneal (into the Peritoneal Cavity)
• It is the Infusion of Injection or fluids in to the peritoneal cavity usually done in peritoneal dialysis to treat chronic Kidney diseases.

Intra cardiac (into the heart)
• Injections that are given directly into the heart muscles or ventricles used in emergencies like administering Adrenaline directly in to the heart during Cardio-Pulmonary Resuscitation

Intra cavernous (in the base of Penis)

• Injection administered into the base of the penis. This injection site is often used to administer medications to check for or treat erectile dysfunction.
• The common medications administered in this route are Caverject, prostaglandin, papaverine, phentolamine, and either atropine or forskolin)

Intra uterine (into the Uterus)

• It is administration of drugs directly in to the uterus.
• Medications like human chorionic Gonadotropin is injected in this route to improve the pregnancy rates in IVF.

Intra vesical (into the bladder)
• It involves instillation of a therapeutic agent directly into the bladder via insertion of a urethral catheter.
• The drug is inserted through a soft catheter that will enter the bladder through your urethra. The drug remains in the bladder for up to 2 hours.
• These drugs directly act on the lining of the bladder without causing major effect on other parts of the body.

Topical Route
• These are drugs applied to the skin are usually used to produce local effects and thus are most commonly used to treat superficial skin disorders, such as psoriasis, eczema, skin infections (viral, bacterial, and fungal), itching, and dry skin.
• The drug is mixed with inactive substances. Depending on the consistency of the inactive substances, the formulation may be an ointment, cream, lotion, solution, powder, or gel.

Sublingual/ Buccal route
• Certain drugs are placed under the tongue (taken sublingually) or between the gums and teeth (Buccal cavity) so that they can dissolve and be absorbed directly into the small blood vessels that lie beneath the tongue. These drugs are not swallowed. The sublingual route is especially good for nitroglycerin, which is used to relieve angina, because absorption is rapid and the drug immediately enters the bloodstream without first passing through the intestinal wall and liver.
• Most of the drugs cannot be taken this way because they may not be absorbed completely.

Rectal route
• When drugs cannot be taken orally due to nausea, vomiting, dysphagia & restrictions in eating, they can also be administered rectally as a suppository. In this form, a drug is
mixed with a waxy substance that dissolves or liquefies after it is inserted into the rectum.
• Because the rectum’s wall is thin and its blood supply rich, the drug is readily absorbed.
• Drugs that can be administered rectally include acetaminophen (for fever), diazepam (for seizures), and laxatives (for constipation).
• Drugs that cause irritating in suppository form may have to be given by injection.

Vaginal route
• Certain drugs may be administered vaginally to women as a solution, tablet, cream, gel, suppository, or ring.
• The drug is slowly absorbed through the vaginal wall.
• This route is often used to give estrogen to women during menopause to relieve vaginal symptoms such as dryness, soreness, and redness.

Ocular Route
• Drugs used to treat eye disorders (such as glaucoma, conjunctivitis, and injuries) can be mixed with inactive substances to make a liquid, gel, or ointment so that they can be applied to the eye.
• Liquid eye drops are easy to administer in ocular route but they can come out off the eye before they are completely absorbed.
• Gel and ointment formulations keep the drug in contact with the eye surface longer, but they may blur vision.

• Solid inserts, which release the drug continuously and slowly, are also available, but they may be hard to insert in and keep in place.
• Drugs like artificial tears prevents eye dryness; beta blockers are administered to treat glaucoma & anti-muscarinic drugs to dilate the pupils.

Otic Route
• Drugs that are administered directly in to the ear.
• Drugs used to treat ear inflammation and infection can be applied directly to the affected ears.
• Ear drops containing solutions or suspensions are typically applied only to the outer ear canal.
• Before applying ear drops, thoroughly clean the ear with a moist cloth and dry it.
• There’s minimal chance of side effect in this route as the drugs do not enter the blood stream unless they are administered for a long time.
• Drugs that can be given by the Otic route include hydrocortisone (to relieve inflammation), ciprofloxacin (to treat infection), and benzocaine (to numb the ear).

Nasal Route
• These are drugs that are breathed in through the nose and absorbed through the thin mucous membrane that lines the nasal passages, and transformed into tiny droplets in air.
• Once absorbed, the drug enters the bloodstream and these drugs exhibit their action quickly. Some of them irritate the nasal passages.
• Drugs that can be administered by the nasal route include nicotine (for smoking cessation), calcitonin (for osteoporosis), sumatriptan (for migraine headaches), and corticosteroids (for allergies).

Inhalation/ Nebulization route
• Drugs administered through inhalation route by the mouth are atomized into smaller droplets than those administered by the nasal route, so that the drugs can pass through the windpipe (trachea) and into the lungs.

. Depending on the size of the droplets these drugs easily enter deep into the lungs. Smaller droplets go deeper, which increases the amount of drug absorbed. Inside the lungs, they are absorbed into the bloodstream.
• Inhalation must be carefully monitored to ensure that a person receives the right amount of drug within a specified time. In addition, specialized equipment like rota Inhalers &  nebulizer systems may be needed to give the drug by this route.
• Aerosolized anti-asthmatic drugs in metered-dose containers (called inhalers), and to administer gases used for general anesthesia are given in this route.

Transdermal Route
• Certain drugs are administered in the body through a patch on the skin. These drugs are sometimes mixed with a chemical (as alcohol) that enhances penetration through the skin into the bloodstream without any injection.
• Through a patch, the drug can be delivered slowly and continuously for many hours or days . As a result, levels of a drug in the blood can be kept relatively constant.
• Patches are particularly useful for drugs that are quickly eliminated from the body and may require to take them frequently.
• Patches may cause skin irritation in certain Individuals. The effects of these drugs depend on how quickly the patches penetrate the skin.
• Only drugs to be given in relatively small daily doses can be given through patches. Examples of such drugs include nitroglycerin (for chest pain), scopolamine (for motion sickness), nicotine (for smoking cessation), clonidine (for high blood pressure), and fentanyl (for pain relief).