ULO 5- Principles of pharmacology, pharmacokinetics and common medication in childbirth Flashcards
Define: Pharmacokinetics
describes the movement of drugs into and inside the body
Define: Pharmacodynamics
is the relationship between drug concentration at the site of action and the resulting effect
includes the mechanisms through which drugs exert their effects on the body
Explain: Precautions, Contraindications and Side-effects
Precautions- measures taken to ensure the woman is safe and minimise adverse outcomes
Contraindications- drug should not be used or recommended
Side-effects- undesirable effects of a drug
Why do some drugs cross the placenta barrier
- it is not an effective barrier to the passage of drugs and
- the blood-brain barrier is underdeveloped in the fetus
- the placenta barrier thins towards the end of pregnancy
Explain: the 3 types of drug names and what they are
Chemical- the active ingredient abbreviated
Generic- simplified chemical name
Trade name- brand, marketed name
Explain: Pharmaceutics
describes the formulation and method of administration of drug
Pharmaceutics
Routes of administration depend on…
the type of formulation
List routes of administration
- Oral
- Nasogastric
- Topical
- Rectal
- Vaginal
- sublingual
Pharmaceutics
Define: Parenteral administration
any method avoiding the GIT
Define the different Parenteral Administration methods
- Intradermal: into dermis
- Subcutaneous: under skin
- Intramuscular: into muscles (butt, thigh)
- Intravenous: into vein
- Epidural: into CFS above dura mater
What factors affect drug storage
- exposure to light
- moisture
- temperature extremes
- expiry dates
- specific needs of sensitive drugs
Pharmacology
What are the 4 processes of Pharmacokinetics
Drug:
- Absoprtion
- Distribution
- Metabolism
- Excretion
Pharmacokinetics
What factors affect drug absorption
- Type of membrane transport (active/passive)
- Epithelial barriers
- Chemical nature of drug (water/lipid based)
- pH of the site of action
- Surface area of drug
- GI tract activities
- Proximity to blood supply
Pharmacokinetics
Define: Dug Distribution
is the movement of the drug from the site of absorption through the body, via the blood stream
Pharmacokinetics
Define: Volume of distribution
the concentration of the drug in the plasma
Pharmacokinetics
Define: Drug Metabolism
the process of chemical alteration of drugs within cells to prepare for excretion
Pharmacokinetics
Define: Bioavailability
the amount of drug available to the body /receptor sites for therapeutic effect
- high with IV, low with oral
Pharmacokinetics
Define: Bioequivalence
describes the equal bioavailability of different formulations of the same drug
Pharmacokinetics
Explain: Life of the Drug in relation to drug excretion
Half Life- time it takes for 1 half of the concentration of the drug to be eliminated from the body
Long half life- active in the body for longer, cannot repeat frequently
Loading/priming dose- for slow to accumulate drugs
Pharmacodynamics
What type of effects do drugs have on the body
- Chemical
- Physical
- Enzyme linked effects
- Receptor effects
Pharmacodynamics
Define: Chemical modes of action
are where the drug chemical reacts with a chemical in the body that is causing a problem
Pharmacodynamics- Drug action at receptors
Describe: Receptors and 2 most important
are specific protein sites on cell membranes where chemicals lock
Agonists- stimulating/promote the natural pathways (Oxytocin/syntocin)
Antagonists- blocking/prevent attachment of natural chemicals (paracetamol)
Pharmacodynamics
Explain: the 4 properties of a drug at a receptor
Affinity- extent of binding
Specificity- selectivity to receptor type
Efficacy- therapeutic effect caused at receptor
Potency- strength of drug required to cause an effect
Pharmacodynamics- Drug Safety
Describe: Therapeutic Index
High TI- safer drug: bigger margin for error allowable
Low TI- more toxic: must be precise
