MDM: Basic of medicine desgin Flashcards
What are the principle objectives for medicine design?
- To acehieve a predcitable therapeutic response from a drug in a formulation
- To manufacture the medicine on large scale with reproducable qualities
Why do we need to formulate a drug into a pharmaceutical dosage form
- To mask unpleasant taste of drugs
- to protect the drug from degradation due to the atmosphere: oxygen, humidity
- To protect the drug from degradation by gastric juices
- To provide site specific delivery
- To provide rate controlled drug action
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Why study pharmaceutics?
- Not all pharmacists work in a dispensary setting e.g. some work in industry researching potential new APIs
- So the pharmacist can answer questions on why one formulation is preferred/ been used over another
- As it gives a rationale why some excipents are included in formulatoins. This allows pharmacists to answer questions
What are some factors to be considered when choosing a particular dosage form
- Patient compliance
- Target population - is it adult/eldery or child. If child is the formulation suitable? is the dose?
- Indication - is it systemic or local?
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What is preformulation?
The study of physiochemical properties prior to drug development
What does preformulation involve?
It is undertaken on lead compounds and will indicate the fesability of potential new dosage forms. Includes testing for instability and poor in vitro dissolution and hence F
What is F?
The fraction of the original dose that reaches the systemic circulation in a chemically unaktered form available to have a therapeutic effect
What are the 3 classes of factors to consider?
- Biopharmaceutical considerations - absorption of the drug from different administration routes
- theraoeutic considerations - patient factors/ indicatio
- drug properties - physiochemical factors
What are biopharmaceutical considerations?
- Relationship between physical, chemical and biological sciences as applied to drugs
- Mechanism of absorption
- distribution
- metabolisam
- excretion
What are therapeutic considerations
- systemic or local?
- Emergency?
- duration of action
- clincial indication
- illness?
What are drug factor consdierations?
- Particle size/ SA
- Solubiity- Poorly soluble drugs become more bioavailable when finely divided i.e. increased surface area.
- Dissolusion
- pKa
- Partion coeficcent
What should the stability of the drug be?
- shelf life 3 years
- look same as when manufactured
- potency should not fall bellow 95%
Physical stability
- • sorption of drug to containers
- • precipitation of drug
- • crystal ripening (Ostwald ripening)
- • creaming & cracking
- • change in mechanical properties e.g. hardness
- • polymorphic change
Chemical stability
- • hydrolysis
- • oxidation
- • dimerisation
- • isomeric change
- • photodegradation
- • excipient compatibility
What is polymorphism what is pseudopolymorphism
polymorph - a material in which the molecules can be arranged in 2 or more ways
pseudopolymorph - a material which molecules can be arranged in 2 or more ways and which have a solvent incoperated into the crystal structure
