Parenteral Products General Introduction, definition, types, advantages and limitations and MCQs for GPAT, NIPER, Pharmacist and Drug Inspector exam
DEFINITION: Parenterals are sterile preparations intended for administration under or through one or more layers of skin or mucous membranes.
The term of parenteral is derived from Greek word para meaning beside and enteron meaning the intestine. Thus parenterals administration should include the administration of drug by any route other than intestine. Parenteral products are considered to be those sterile drugs, solutions, emulsions, suspensions.
Parenteral products are unique from any other type of pharmaceutical dosage form for the following reasons:
- All products must be sterile.
- All products must be free from pyrogenic (endotoxin) contamination.
- Injectable solutions must be free from visible particulate matter. This includes reconstituted sterile powders.
- Products should be isotonic, although strictness of isotonicity depends on the route of administration. Products administered into the cerebrospinal fluid must be isotonic. Ophthalmic products, although not parenteral, must also be isotonic. Products to be administered by bolus injection by routes other than intravenous (IV) should be isotonic, or at least very close to isotonicity. IV infusions must be isotonic.
- All products must be stable, not only chemically and physically like all other dosage forms, but also ‘stable’ microbiologically (i.e., sterility, freedom from pyrogenic and visible particulate contamination must be maintained throughout the shelf life of the product).
- Products must be compatible, if applicable, with IV diluents, delivery systems, and other drug products co-administered.
ADVANTAGES:
- The parenterals are administration of unconscious patients.
- Who can not take oral administration.
- They are free from pyrogen.
- Low toxicity as compared to solid dosage forms.
- 100% bioavailability.
- No chance of missing dose.
DISADVANTAGES:
- Requirement of aseptic technique in production compounding and handling of products.
- Requirement of trained personnel for administration.
- Real or psychological pain associated with the injection.
- Highly risky if any mistake at happens any point.
- High cost as compared to solid dosage forms.
Parenteral Routes of Administration:
1. Intravenous Route: IV injection of drugs had its scientific origin in 1656 in the experiments of Sir Christopher Wren, architect of St Paul’s Cathedral and amateur physiologist. IV drugs provide rapid action compared with other routes of administration, and because drug absorption is not a factor, optimum blood levels may be achieved with accuracy and immediacy not possible by other routes. In emergencies, IV administration of a drug may be lifesaving because of the placement of the drug directly into the circulation and the prompt action that ensues. On the negative side, once a drug is administered intravenously, it cannot be retrieved. Both small and large volumes of drug solutions may be administered intravenously.
2. Intramuscular Route: IM injections of drugs provide effects that are less rapid but generally longer lasting than those obtained from IV administration. Aqueous or oleaginous solutions or suspensions of drug substances may be administered intramuscularly. IM injections are performed deep into the skeletal muscles. In adults, the upper outer quadrant of the gluteus maximus is the most frequently used site for IM injection. In infants, the gluteal area is small and composed primarily of fat, not muscle. The muscle is poorly developed. In infants and young children, the deltoid muscles of the upper arm or the midlateral muscles of the thigh are preferred. The volume of medication that may be conveniently administered by the IM route is limited, generally to a maximum of 5 mL in the gluteal region and 2 mL in the deltoid of the arm.
3. Subcutaneous Route: The SC route may be used for injection of small amounts of medication. Injection of a drug beneath the skin is usually made in the loose interstitial tissue of the outer upper arm, the anterior thigh, or the lower abdomen. The site of injection is usually rotated when injections are frequently given, as with daily insulin injections. The maximum amount of medication that can be comfortably injected subcutaneously is about 1.3 mL, and amounts greater than 2 mL will most likely cause painful pressure. Syringes with up to 3-mL capacities and 24- to 26-gauge needles are used. These needles have cannula lengths of three-eighths of an inch to an inch. Most typically, SC insulin needles are 25 to 30 gauge with length of five-sixteenth to five-eighth of an inch.
4. Intradermal Route: A number of substances may be effectively injected into the corium, the more vascular layer of the skin just beneath the epidermis. These substances include various agents for diagnostic determinations, desensitization, or immunization. The usual site for ID injection is the anterior forearm. A short (three-eighth of an inch) and narrow (23- to 26-gauge) needle is usually employed. The needle is inserted horizontally into the skin, with the bevel facing up. The injection is made with the bevel just disappearing into the corium. Usually, only about 0.1 mL may be administered in this manner.
5. Specialized Access: When it is necessary to administer repeated injections over time, it is prudent to employ devices that provide continued access and reduce pain associated with administration. Several types of central venous catheters are used in institutions and on an outpatient basis for a variety of parenteral medications (e.g., cancer chemotherapy, long-term antibiotic therapy, TPN solutions). They can remain in place for a few days to several months. When not in use, they require heparinization to maintain patency of the catheter lumen.
Types of parenterals: According to the USP, injectable materials are separated into five general types. These may contain buffers, preservatives, and other added substances:
1. Injection: Liquid preparations that are drug substances or solutions thereof (e.g., Insulin Injection, USP).
2.For injection: Dry solids that, upon addition of suitable vehicles, yield solutions conforming in all respects to the requirements for injections (e.g., Cefuroxime for Injection, USP).
3.Injectable emulsion: Liquid preparation of drug substance dissolved or dispersed in a suitable emulsion medium (e.g., Propofol, USP).
4.Injectable suspension: Liquid preparation of solid suspended in a suitable liquid medium (e.g., Methylprednisolone Acetate Suspension, USP).
5.For injectable suspension: Dry solid that, upon addition of suitable vehicle, yields preparation conforming in all respects to the requirements for injectable suspensions (e.g., Imipenem and Cilastatin for Injectable Suspension, USP.
Multiple choice questions:
1.Parenterals are sterile preparations intended for administration under or through one or more layers of skin or mucous membranes.
a)true
b)false
2.The term of parenteral is derived from Greek word para meaning intestine and enteron meaning the beside.
a)true
b)false
3. Parenteral products are considered to be those sterile drugs and
a)solutions
b)emulsions
c)suspensions
d)all of these
4.Parenteral products are unique from any other type of pharmaceutical dosage form for the following reasons
a)All products must be sterile
b)All products must be free from pyrogenic (endotoxin) contamination
c)Injectable solutions must be free from visible particulate matter
d)All of these
5.Pyrogens are
a)exotoxin
b)endotoxin
c)both of these
d)none of these
6.Which of the following products must be isotonic?
a)Products administered into the cerebrospinal fluid
b)IV infusions
c)Products to be administered by bolus injection by routes other than intravenous
d)All of these
7.Which of the following is not an advantage of parenterals?
a)The parenterals are administration of unconscious patients
b)Who can not take oral administration
c)They are free from pyrogen
d)Requirement of aseptic technique in production compounding and handling of products
8.Which of the following gives 100% bioavailability?
a)Tablets
b)Capsules
c)IV injections
d)Suspensions
9.Which of the following is/are disadvantages of parenterals?
a)Requirement of trained personnel for administration
b)Real or psychological pain associated with the injection
c)Highly risky if any mistake at happens any point
d)All of these
10.Which of the following is not parenteral route of administration?
a)IV
b)IM
c)Subcutaeous
d)Sublingual
11.IV drugs provide rapid action compared with other routes of administration, and because drug absorption is not a factor, optimum blood levels may be achieved with accuracy and immediacy not possible by other routes.
a)true
b)false
12.Which of the following can be administered intramuscularly?
a)Aqueous suspensions
b)Oleaginous solutions
c)Oleaginous solutions
d)All of these
13.Which of the following is the most frequently used site for IM injection in adults?
a)upper outer quadrant of the gluteus maximus
b)deltoid muscles of the upper arm
c)midlateral muscles of the thigh
d)all of these
14.Which of the following is the most frequently used site for IM injection in infants?
a)upper outer quadrant of the gluteus maximus
b)deltoid muscles of the upper arm
c)midlateral muscles of the thigh
d)b and c
15.Most typically, SC insulin needles are ____ gauge with length of five-sixteenth to five-eighth of an inch.
a)25 to 30 gauge
b)23- to 26-gauge
c)10 to 20 gauge
d)all of these
Solutions:
- a)true
- b)false
- d)all of these
- d)All of these
- b)endotoxin
- d)All of these
- d)Requirement of aseptic technique in production compounding and handling of products
- c)IV injections
- d)All of these
- d)Sublingual
- a)true
- d)All of these
- a)upper outer quadrant of the gluteus maximus
- d)b and c
- a)25 to 30 gauge
References:
- Remington Essential of Pharmaceutics, 1st edition 2013, page no. 495.
- Ansel’s Pharmaceutical Dosage Forms and Drug Delivery Systems, 10th edition, page no. 508-514.
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