Drug Delivery Flashcards
What characteristics of the patient influence drug formulation?
- Patients Needs
- Their disease state
- Their pharmacological characteristics.
What 5 things are to be considered when determining dosage regime?
- Any renal/hepatic failure
- The recommended doses
- Age & weight
- Disease
- Drugs Toxicity
Where are oral meds absorbed into systemic circulation?
Oral meds absorped in the GI tract
Define a suspension:
Coarse drug particles in a liquid phase
What type of drugs are used in suspension?
Insoluble & unpalatable drugs
What type of patients would use solutoins/suspensions over tablets?
People with swallowing difficulties including the very young & old.
How are solution & suspensions delivered?
By naso-gastric or Peg tubes
What is the rate limitng step in tablet absorption?
The tablets break down or “dissolution”
What are the main advantages of tablet/capsule drugs?
- convenient to use
- accurate doses
- easily reproducible in mass
- high drug stability
Why would you use an enteric coating on a tablet?
Protect from destructive stomach acid (Allowing it to reach the small intestine) or protect stomach from a toxic drug
What drugs are enteric coated & why?
Omeprazole, to protect it from stomach acid
Aspirin to protect the stomach from it.
Why don’t enteric coated tablets disintegrate till they reach the small intestine?
Only disintegrate in higher pHs, stomach is very acidic so unchanged in it
What are the advantages o prodrugs?
Avoid drug degradation in gut
Prolong duration of action
What does a prolonged release formulation do?
Maintains drug level within therapeutic range over a longer period
How does using prolonged release formulations improve patient compliance?
Prolonged release formulations need less frequent doses, increasing odds a patient will take them all
In what 3 forms do prolonged release formulation geerally come?
Oral tablets
Intramuscular Injection
Surgical implants
What drugs are delivered by surgical implant?
Progesterone (contraception)
Testosterone
What drugs are ideal for buccal/sublingual administration?
large amount of pre-systemic or first pass metabolism
Do rectally delivered drugs treat locally or systemically?
both local & systemic conditions
For what type of patient are rectal route drugs useful?
those unable to swallow
In what forms do rectal drugs come?
Creams
Liquids
Suppositories
Do drugs delivered vaginally treat locally or systemically?
Vaginal route drugs treat local disease
In what form are most vaginal route drugs?
Creams
For what type of patient are IV drugs especiall useful?
Unconscious or comatose patients
Why is IV good for drugs with short half-lives?
Allows constant infusion so drug level remains within therapeutic range
(instant of spiking & dropping with doses)
Are IV drugs rapid or slow release?
IV drugs have rapid systemic effects
For what type of drugs is IV delivery especially useful.
Short half life drugs
Drugs with narrow therapeutic index
what type of drugs are delivered intramuscularly
Insoluble drugs or those fomrualted in an oil base
Examples of drugs given by subcutaenous injection?
Heparin
Insulin
Narcotic Analgesics
How long do intramuscular injected drugs work?
Drugs injected intramuscularly can have sustained effects of up to months
You cant see a patients veins but desperately need to deliver fluid what method do you use?
Subcutaneuous injection
In what ways are subcutaneous injections deivered?
- Dermojet (needles)
- Solid pellet implanted below skin
- Pumps (e.g. insulin pump)
Drug is delivered via an adhesive patch on the skin, what delivery method is this?
Transdermal delivery
How are transdermal drugs absorbed into circulation?
They cross skin by percutaneous absorbtion
What is percutaneous absorbtion?
Absorption of a substance through unbroken skin
Are transdermal drugs used for local or systemic effect?
Transdermal drugs can be systemic or local
Are inhalation drugs used for local or systemic efects?
Inhalation drugs have local effects.
Only inhaled anaesthetics are systemic.
Why are inhalation drugs useful?
Drugs delivered direct to site of action with rapid effect & no first pass metabolism.
Why do inhaled drugs only need small doses?
Only around 5-10% is absorbed systemically so the dose doesnt need to account for absorbtion or metabolism.
Are inhaled drugs more less toxic?
Administering drugs by inhalation actually reduced adverse effect
Name 4 carier based systems:
- Monoclonal antibodies
- Liposomal carriers
- Nanoparticles
- Genetic transfer systems
What do monoclonal antibodies do?
Bind to cancer-specific antigens
Induce immunological response against cancer
What is a liposomal carrier?
Liposome packed with drugs, transports through the blood
How do liposomal carriers affect the drugs pharmacokinetics?
Accumulate at disease sites
Reduced distribution at sensitive tissue
Whats the main benefit of nanoparticle carriers?
Allow specific targeting/delivery of drugs.
What effect do nanoparticles have on treatment?
The drug has reduced toxicity while maintaining therapeutic efficiency (beacue its targeted)
What type of organisms are used as vectors for genetic transfer?
Viruses
How are viruses altered for genetic transfer systems?
Virus has genes for viral replication removed and therapeutic genes inserted
What does a genetic transfer system do?
Altered virus delivers therapeutic gene to target cells
