Written By: Nisha Joshi
Drugs can be administered via various routes. Route of drug administration depends on Properties of the drug, therapeutic objectives and Patient factor.
- Properties of drug: Solubility, ionization, pH, irritancy
- Therapeutic objectives: site of action, rapidity of treatment
- Patient factor: condition of patient
Route of drug administration can be divided as:
- Enteral
- Oral
- Enteric coated preparation
- Extended release preparation
- Sublingual/ buccal
- Parenteral
- Intravenous
- Intramuscular
- Subcutaneous
Other route of drug administration:
- Inhalation
ii. Topical
iii. Transdermal
iv. Rectal
v. Intrathecal/ Intraventicular
vi. Intra arterial
vii. Intra pleural
viii.Intraperitoneal
ix. Intra articular
x. Intra ocular
xi. Intra amniotic
- Enteral route of drug administration:
In enteral route of drug administration, drug is administered by a mouth. It is the safest, most common, convenient and economic method of drug administration.
- Oral Route:
Oral route can easily be self administered. It has low risk of systemic infection. One can use antidotes if toxicity and overdose occur.
- Enteric coated preparation: These preparations are coated with polymer that resist the action of fluid and enzyme in the stomach but dissolves in upper intestine. In some drugs, coating is done to overcome the drugs irritating action (aspirin).
- Extended release preparation: These preparations have special coating which controls how fast the drug is released from the pill into the body. It has longer duration of action which improve the patient’s compliance. It is advantageous for the drug with short half life.
- Sublingual/ Buccal route of drug administration:
In this route of drug administration, drug is placed under the tongue which allow to diffuse into the capillary network. Drugs enter the systemic circulation directly. This route helps rapid absorption. It has low incidence of infection. It avoids first pass metabolism.
- Parenteral Route of drug administration:
Parenteral route of drug administration are those route of administration in which drug are introduced directly across the body’s barrier into systemic circulation.
These routes are used for those drugs that are poorly absorbed from GIT, unstable in GIT, to treat unconscious patients and in the circumstances that require rapid onset of action. This route of drug administration has the highest bioavailability. This route provides the most controlled over the actual dose of drug delivered to the body.
As this route of drug administration is irreversible and it may cause pain, local tissue damage, infection and fever.
- Intravenous (IV) route of drug administration:
It is the most common route of parenteral route of drug administration. It is given in one of the superficial vein. It is used for the drug that are not absorbed orally.
It is given as bolus if the full amount of drug has to be delivered to systemic circulation immediately.
It is given as infusion during longer time resulting in decrease in peak plasma concentration and increase in time the drug is present in circulation.
Only aqueous solutions can be used by this route.
It is the most risky route because the vital organs are exposed to high concentration of drug and chances of contamination is high.
- Intramuscular (IM) route of drug administration:
In this route of drug administration, drugs are given either as aqueous solution (absorbed rapidly) or depot preparation (absorbed slowly). Drugs are injected in one of the large skeletal muscle. The absorption of the aqueous solution is faster (vascular) and mild irritants can be injected (less richly supplied with sensory nerves). This route has to be avoided in anticoagulant treated patient because it can produce local hematoma.
- Subcutaneous (SC) route:
In this route, drug is deposited in loose subcutaneous tissue. If the drug are irritant, those drugs should not be injected via this route (as in this route drug are richly supplied by nerves). The absorption is slower than IM route. The risk of hemolysis or thrombosis is less. Self injection is possible. Depot preparation can also be injected.
Others:
- Inhalation:
This route of drug administration drug is used to produce either localized or systemic drug effect. The drugs that are gases and those that can be dispersed in an aerosol are used as inhalation route of drug administration. This route is effective in the patients with respiratory complaints, direct delivery, less systemic side effect. Systemic effect is observed when general anesthetics are inhaled.
- Topical:
In this route of drug administration, drugs are applied to the area on or in the body to provide the local effect. It is generally used to treat the disorders of the skin, eye, nose, mouth, throat, rectum and vagina.
- Transdermal:
In this route of drug administration, drugs are delivered across the skin for systemic distribution as a transdermal patches or ointment. It is often use for sustained delivery of drugs.
- Rectal:
In this route of drug administration, drugs are delivered via rectum which are absorbed by the rectum's blood vessels, and flow into the body's circulatory system and distributes the drug to the body's organs and systems. It is useful if the drug induce vomiting when given orally or patient is already unconscious or vomiting.
- Intrathecal/Intraventricular:
In this route of drug administration, drugs are delivered via ventricular puncture into the spinal canal, or into the subarachnoid space so that it reaches the cerebrospinal fluid (CSF). It ensures the selective regional delivery and eliminate the risk of systemic side effect.
- Intra pleural:
In this route of drug administration, drugs are injected through the chest wall into the pleural space or instilled through a chest tube placed intra pleurally for the drainage.
- Intraperitoneal:
In this route of drug administration, drugs are injected into the peritoneum i.e. body cavity.
- Intra articular:
In this route of drug administration, drugs are injected into joint cavity.
- Intra ocular:
In this route of drug administration, drugs within the eye.