Parenterals Flashcards
1
Q
Advantages of parenteral administration
A
- Viable in emergency
- Provides accurate dosage
- Localized effect
- Fastest action
- Prolonged action
- alternative to other routes of delivery
- avoid GI enzymatic degradation and instability
- avoid low and variable absorption
2
Q
Disadvantages of parenteral administration
A
- Painful
- Need trained personnel to administer
- Rapid action -> difficult to reverse drug’s effects
- Needle problems
- High cost of manufacturing
- Strict packaging requirements
3
Q
Routes of parenterals administration
A
- subcutaneous (SC) - injection beneath the surface of the skin in small amounts 1.3 mL
- intravenous (IV) - rapid action, accurate, lifesaving in emergency
- intramuscular (IM) - drug action is less rapid but of greater duration compared to IV route, injected in skeletal muscles away from major nerves and vessels
- intradermal
4
Q
Official types of injections
A
- Injection: liquid preparations that are drug solutions/substances (e.g. insulin injections); dry solids/concentrate -> need addition of solvent
- Injectable emulsion (can be injected in muscles but not in veins): drug dissolved/dispersed in an emulsion medium (e.g. Propofol)
- Injectable suspension: Preparation of solids in a liquid medium (e.g. Methyl prednisolone acetate suspension)
5
Q
Characteristics of parenterals
A
- sterile
- pyrogen-free
- particulate free
6
Q
Requirements for solutions and suspensions to be used for injections
A
- solvents/vehicles must meet purity and safety standards
- Must be sterile and pyrogen-free
- Must be prepared under aseptic conditions
- Restrictions on buffers, stabilizers, antimicrobial preservative
- Coloring agent strictly prohibited
- Must meet standards for particulate matter
- Packaged in hermetic containers of specific and high quality
- Filled in slight excess for easy withdrawal
- Sterilized powders intended for solutions/suspensions are packed as lyophilized/freeze-dried powders
- Specific labeling regulations apply
7
Q
What is lyophilization (freeze-drying) and its steps?
A
Process of drying in which water is sublimed from the product after it is frozen
- Freezing an aqueous product
- Evacuate the chamber
- Introducing heat to the product to allow for subliming of ice into a cold condensing surface
8
Q
Ingredients for parenterals
A
- Vehicle
- buffers
- antioxidants
- antibacterial agents
- tonicity materials: dextrose, glycerin, mannitol, NaCl
- Surfactants: egg and soybean phospholipids and lecithin
- thickeners
- preservatives: multidose containers
- Solubilizers, protectants, wetting agents emulsifiers, local anesthetics
9
Q
Ingredients for parenterals: Types of Vehicles
A
- Aqueous vehicles: water most frequently used and preferred (E.g. water for injection USP/Purified water USP, sterile water for injection USP, bacteriostatic water for injection USP, sterile water for irrigation)
- Water-miscible vehicles: increase drug solubility and/or reduce hydrolysis -> stability (e.g. ethanol, propylene glycol, polyethylene glycol 300)
- Non-aqueous vehicles: pure sterile, must remain clear on cooling to 10C, use is confined to IM injections, can be irritating and allergic reactions can occur (e.g. peanut oil - dimercaprol, cotton seed oil - estradiol cypionate, castor oil - estradiol valerate)
10
Q
Ingredients for parenterals: Buffers
A
- Maintains pH, stability and prevent degradation
- Blood pH 7.4
- e.g. monosodium phosphate/disodium phosphate -> pKa 7.21
- e.g. disodium citrate/trisodium citrate -> pKa 6.4
11
Q
Ingredients for parenterals: Antioxidants
A
- Prevent the oxidization process by blocking the oxidization process or being oxidized faster than the drug
- air is displaced with inert gas (N2) -> prevent chemical reactions
- e.g. (water-soluble): ascorbic acid, sodium sulfite, sodium bisulfite, (oil-soluble): butylated hydroxytoluene and hydroxyanisole
12
Q
Ingredients for parenterals: Antibacterial agents
A
- prevent microbial growth and multiplication
- use limited concentration
- effectiveness varies with formulation
- refrigeration slow the growth but does not prevent it
13
Q
How to determine the effectiveness of an antimicrobial system for a parenteral
A
- Inoculums containing a known number of organisms (Candida albecans, Aspergillus niger,..) is added
- incubate at 32C for few days
- > Result: adequate if no significant rise in microorganisms
14
Q
Ingredients for parenterals: Tonicity agents
A
- routes that require isotonicity: intrathecal, intraarticular, intradermal
- decrease pain of injection and tissue irritation
- decrease hemolysis of blood cells
- prevent electrolyte imbalance
- can include buffers: sodium chloride (0.9%), potassium chloride, dextrose (5.5%), mannitol, sorbitol, lactose
15
Q
Ingredients for parenterals: Protectants
A
- Sugars that form glasses at low temp
- Used to maintain the chemical and physical stability of drugs that are frozen and freeze-dried: protein drugs and some peptide antibiotics
16
Q
Other parenteral adjuncts
A
- suspending/viscosity increasing agents: sodium carboxymethyl cellulose, gelatin, methylcellulose
- Chelating agents: ethylenediamine tetraacetic acid
- Inert gases: N2, CO2
- Adjuncts influencing solubility: sodium benzoate to solubilize caffeine, ethylene diamine to solubilize theophylline
17
Q
Aseptic procedures use
A
- UV lights
- Filtered air supply
- Sterile equipment
18
Q
Packaging of injections
A
- Packaged to maintain product sterility until time of use
- containers must not interact with the preparation
- types of containers: glass and plastic polymers
- plastic bags
- dual chamber vials
- cartridges and delivery pens
19
Q
Parenteral Incompabilities
A
- Physical - visible change in solution appearance e.g. precipitation, color, gas formation
- Chemical - chemical change -> toxicity/therapeutic inactivity (not always visible) - hydrolysis, complexation, oxidation, photolysis
- Therapeutic - change in activity e.g. cortisone antagonizing heparin
20
Q
Available injections
A
- Small volume parenterals (SVP) - 25-50 ml
- Can be in solution/suspensions, emulsions, solids
- premixed, ready to use -> require little/no manipulation
- Little wastage
- do not offer flexibility in quantity/concentration
- some products require thawing -> microwave - Large volume parenterals (LVP) - 100 ml - 1L or more per day
- Flexible but requires manipulation
- Usually administered by IV infusion to replenish body fluids, electrolytes, or to provide nutrition
- Should not contain bacteriostatic/pharmaceutical additives
- Contain electrolytes, carbohydrates, proteins, fatty emulsions
21
Q
LVPs is employed for
A
- Maintenance therapy: For patients entering/recovering from surgery and for those who are unconscious and unable to take nutrients;
Total parenteral nutrition (TPN) provided if oral feeding must be differed for period of weekls/longer to provide all essential nutrients to minimise tissue breakdown and maintain normacy;
Total nutrient admixtures (TNA) include all substrates necessary for nutritional support (carbohydrates, proteins, fats, electrolytes and trace elements) - Replacement therapy: heavy loss of water and electrolytes need to be replaced; for patients with vomiting, diarrhea…
22
Q
What are irrigation solutions
A
- intended to bath/wash wounds, surgical incisions or body tissues (during operations)
- subjected to same stringent standard as for parenteral preparations
e. g. sodium chloride irrigation, USP 0.9% NaCl used to wash wounds and employed as enema
23
Q
What is dialysis
A
Separation of substances from one another in solution by taking advantage of their differing diffusibility through membranes
24
Q
What does dialysis solutions usually contain
A
- Dextrose
- Vitamins
- Electrolytes
- Amino acids
