Parenteral drug delivery Flashcards
Parenteral drug delivery is delivery that bypasses the alimentary canal. TRUE OR FALSE?
TRUE
Parenteral delivery sually deleivers solutions, suspensions and emulsions. TRUE OR FALSE?
TRUE
The site of injection bypasses the skin which is one of the major body barriers. TRUE OR FALSE?
TRUE
What are the three types of parenteral injection?
- Subcutaneous
- Intramscular
- Intravenous
Describe the I.V route?
- Delivers the formulation to a large vein usually a large proximal vein
- Rapid response
- 100% bioavailability
- Different volumes can be administered
- Usually solutions and emulsions, not suitabel for suspensions
- Can be used to deliver drugs that are irritating by other routes
Describe the I.M route
- Into the muscle
- Small volume of injection
- Onset is formulation dependant (controlled release formulation/fast onset)
Describe S.B route
- Injection into s.c fat (arms, leg, abdomen)
- Formulation dependant
- slow release from oily or viscosity vehicles
- Normally a small 1ml injection volume - which limits potential application
What are some ads of injections ?
- Quick onset and physiological response
- Bioavailability / avoids first pass metabolism of oral route
- Deliver drugs unresponsive
- Usually not adminsitered by patients so good control of dosage and frequency
- Can rapidly achieve local effects
- Formulation and use of infusion can allow a wide range of therapies to be considered
What are some disads for injections?
- Cost is significantly greater compared to toher dosage forms (requires clean room technology)
- Administration (painful/special skills required/difficult to reverse side effects once administered)
What are the formualtions for parenteral delivery?
- Solutiond (oil or water based)
- Suspensions (oil or water based)
- Emulsions (oil in water)
What factors affect choice of formulation?
- Physicochemical properties of the drug
- Route of admin
- Amount to be admin
- Preference for formulation type may be based on previous clinical experience and performance
What does good, moderate and low solubility mean?
Good : Can be readilty formulated in a suitable vehicle
Moderate: reasonable but possibly not sufficient solubility for therapeutic needs
Low: usually formulated in suspension form
Provide examples of non-aqueous solvents?
-Oils (corn oil)
What is the aim when co-solvents are used and give an example of one?
-Aim is to render the active drug soluble and allow it to be delivered while reducing or minimising pain and discomfort e.g glycerol and ethanol
Large volumes are usually given I.v, smaller volumes are given via othe routes. TRUE OR FALSE?
TRUE
S.c and i.m are slower than i.v. TRUE OR FALSE?
TRUE
Absorption is faster from aqueous solutions than othe formulations when given i.m or s.c . TRUE OR FALSE?
TRUE
Slower release from suspensions and emulsions cannot be used for prolonged, controlled release formulations. TRUE OR FALSE?
FALSE
What is a crystalline structure?
-Repeating ordered structures, usually therefore have higher melting point than amorphous materials
Polymorphic materials have the same chemical structure but different physical forms, therefore different melting points and different rates of dissolution, hence affecting bioavailability. TRUE OR FALSE?
TRUE
Provide examples of polymorphism?
- paracetamol
- spironolactone
What does particle size affect?
- Absorption and dissolution
- Stability of the drug in the dosage form
The rate of dissolution of poorly soluble drugs increaseas as the surafce area increases. TRUE OR FALSE?
TRUE
Smaller particle size may result in greater rate of dissolution for poorly soluble drugs. TRUE OR FALSE?
TRUE
Not all salt forms have the same solubility. TRUE OR FALSE?
TRUE
Certain counter ions are used to enhance solubility/dissolution and bioavailability. TRUE OR FALSE?
TRUE
What does salt form affect?
- Stability
- Solubility
- Dissolution rate
- Crystal form/polymorphism
- Mechanical properties
For stable salt formation, ionisation must not be in effect, complete such that a single ionisation state is formed. TRUE OR FALSE?
FALSE
What are some commonly used salts?
-For basic drugs
(hydrochloride,sulphate, maleate)
-For acidic drugs
(K,Na,Li,Mg,Ca)
Materials thata re too alkaline might degrade glass during storage. TRUE OR FALSE?
TRUE
What is water for injection used for?
-Used for soluble and poorly soluble agents and as the aqueous phase of an emulsion
What pH range is used for water for injection BP?
5-7
What are pyrogens?
-Fever producing compounds usually from bacteria
What are non-aqueous vehicles used for?
-For non-water-soluble therapeutic agents
What materials are used in non-aqueous vehicles?
-Non volatile oil, e.g corn oil, sesame seed oil - good stability
What are the problems with non-aqueous vehicles?
- Pain (irritation upon injection often due to viscosity effects at different temperatures
- Sensitivity (peanut oils and allergies
- Enhancers
Isotonicity is best for all injections. TRUE OR FALSE?
TRUE
At what temperature does an isotonic solution freeze?
-0.52 degrees
A 1% w/v solution of sodium chloride depresses the freezing point by 0.576 degrees. TRUE OR FALSE?
TRUE
A 1% w/v soltuion of ephedrine hydrochloride depresses the freezing point by 0.169 degrees. TRUE OR FALSE?
TRUE
What are the regulatory requirements for injection maufacture?
- Buildings and facilitites
- Personnel, training, qualifications
- Components and containers
- Endotoxin control
- Validation processes
- Laboratory control
- Sterility testing
