Parenteral Route of Drug Administration
The term parenteral is used when drug is administered through other than enteral route and systemic action is required. Desired effect is systemic, substance is given by routes other than the digestive tract or topical application.
Types of Parenteral Routes
- Intravenous also popularly known as I.V. which is given directly into a vein with injection. As the drug direclty gose in to the systemic circulation, the rapidally reaches to the site of action and the onset of action is quick (within minuets) e.g. many drugs, total parenteral nutrition.
- Intra-arterial is given into an artery through injection, e.g. vasodilator drugs in the treatment of vasospasm and thrombolytic drugs for treatment of embolism. The onset of action is similar to IV route.
- Intraosseous infusion (into the bone marrow) is, in effect, 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-muscular injection given to the muscular part of the body.
- Intrathecal: Drug is direcly administered in to the spinal cord
Advantages of Parenteral Drug Administration
Parenteral drug is idministered with the use of injections. In market formulations like ampoules, vials and sometimes readymade syringes (Insulin) are available for injecteble drugs. The Parenteral rout maily encompasses intravenous (IV), intramuscular (IM), and subcutaneous (subcut)
- Onset of action is very fast 15–30 seconds for IV, 3–5 minutes for IM and subcutaneous (subcut)
- Bioavailability of drug is 100%
- Suitable for drugs not absorbed by the gut or those that are too irritant (anti-cancer)
- One injection can be formulated to last days or even months, e.g., Depo-Provera, a birth control shot that works for three months
- IV can deliver continuous medication, e.g., morphine for patients in continuous pain, or saline drip for people needing fluids
- In a case when patient is not able to take drug through GI route (unconcious or mergency)
Disadvantages of Parenteral Drug Administration
- More risk of addiction when it comes to injecting drugs of abuse, as onset of action is quick,
- Route is not feasible as patients are not typically able to self-administer
- Belonephobia, the fear of needles and injection.
- High risk of HIV and other infectious diseases, if needles are shared
- It is the most dangerous route of administration because it bypasses most of the body's natural defenses, exposing the user to health problems such as hepatitis, abscesses, infections, and undissolved particles or additives/contaminants
- If proper care is not taken while injecting, potentially fatal air boluses (bubbles) can occur.
- Strict asepsis is needed
- The cost of injection is hifher than tablets, capsules or other oral dosage forms