Definition: Parenteral preparations are sterile, pyrogen-free liquids (solutions, emulsions, or suspensions) or solid dosage forms packaged in either single-dose or multidose containers.
- These preparations are administered through the skin or mucus membranes into internal body compartments.
- These include any method of administration that does not involve passage through the digestive tract.
The term parenteral is derived from the Greek word Para – outside and Enter one Intestine. It denotes the route other than oral.
History: In 1492, Pope Innocent had received a transfusion from young boys. In 1656, Christopher Wren used a sharpened hollow quill of a feather to inject crude extract of opium into the vein of a dog. J. D. Major and Johannes Elsholtz were the first who successfully injected humans in 1662 using solutions of opium. In the 1850s Alexander Wood was credited to give subcutaneous injections using a true hypodermic syringe. Today, parenteral dosage forms are available with high standards.
- If the drug is not absorbed orally it can be given parenterally.
- A drug that is unstable in GIT can be given parenterally.
- Drugs that are undergoing extensive first-pass metabolism are given parentally which avoids the first-pass metabolism.
- When patients need rapid drug action in emergencies as the onset of action of parenteral is rapid.
- The patient is uncooperative/unconscious (accident, surgery, etc.).
- Complete drug bioavailability (up to 100%) is possible.
- Prolonged drug action is possible.
- Parenteral therapy provides the means of correcting serious disturbances of fluid and electronic balances.
- When food cannot be taken by mouth, the total nutritional requirement can be supplied by the parenteral route.
- Patient compliance problems are largely avoided.
- Most inconvenient route of administration /pain upon injection.
- Generally, need a medical expert for administration (like physician or nurse usually in hospital or clinic).
- If administered by patients themselves, need good training.
- It requires strict adherence to aseptic procedures.
- It requires more time than those administered by other routes.
- Chances of improper dosing are more.
- Chances of adverse effects are more.
- The danger of blood clot formation is there.
- Drug cannot be recovered in adverse conditions as it is irreversible.
- The manufacturing and packaging requirements of parenteral dosage forms are more costly than other dosage forms.
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