⭐ LECTURE 2: PHARMACOTHERAPEUTICS Flashcards
What are the SIX types of THERAPIES?
Acute Therapy
Maintenance Therapy – common in elderly
Supplemental Therapy
Palliative Therapy
Supportive Therapy
Prophylactic Therapy – give medication to prevent certain kinds of diseases
Ratio between a drug’s therapeutic benefits and its toxic effects
Benefits > toxic effects
Therapeutic Index
decreasing response to a repetitive drug
Tolerance
physiological or psychological need for a drug
Dependence
Alteration of action of a drug by:
Other prescribed drug
OTC medications
Herbal therapies
Interactions
Preventable, Medication errors that may result in patient harm
Adverse drug EVENTS
Inherent and not preventable
Unexpected, undesirable, and occurs at doses normally used
Adverse drug REACTIONS
What are the undesirable response to drug therapy
Idiosyncratic,
Hypersensitivity reactions,
Drug interactions, Iatrogenic Responses
unintentional adverse effects that are treatment-induced
Iatrogenic Responses
What are the SIX factors influencing the efficacy of a drug?
- Route of Administration
- Rate of Absorption
- Distribution of the drug to the required site
- Rate of biotransformation or metabolism
- Presence of active metabolite
- Rate of excretion
Ability of the drug to cross the cell membrane is influenced by its solubility in water or fat, its size and shape
Absorption
What orally prepared drug has the FASTEST drug absorption rate?
Liquids, elixirs, syrups
What orally prepared drug has the SLOWEST drug absorption rate?
Enteric-coated tablets
Small water-soluble molecules which flow through the hydrophilic pores
Filtration
diffusion (high to low concentration)
Passive Transport
energy and carriers are required to move non-fat soluble substances across the cell membrane
Active Transport
What are the FIVE factors affecting the absorption rate (ka)?
Blood supply to the site of absorption
Formulation of the drug
Gut transit time
pH in the gut
Solubility of the product
How the drug is distributed through the bloodstream
Distribution
Major organs and blood vessels
Low lipid solubility (hydrophilic)
Low Vd
Central Compartment
Skin and fat stores
High lipid solubility (lipophilic)
High Vd
Peripheral Compartment
Amount of drug in the body to the concentration in the plasma
Volume Distribution (Vd)
Only free fraction can move to target site (ratio of 80% bound : 20% free)
Plasma protein binding
Active metabolites have more side effects than inactive metabolites
Metabolism
major organ of metabolism
Liver
What are the factors affecting metabolism?
Genetic factors
Other drugs
Smoking
Enzyme induction/inhibition
Some foods
Liver disease
Age
Drug passes the liver before going into circulation
FIRST-PASS EFFECT
extensively metabolized by the liver before reaching the systemic circulation (high first-pass effect)
Oral route
bypasses the liver (prevents the first-pass effect)
IV
Metabolism of orally administered drugs in a single passage thru the gut wall and the liver
First-Pass (Presystemic Metabolism)
What are the TEN routes that bypass the liver?
Sublingual
Transdermal
Buccal
Vaginal
Rectal (high first pass)
IM
IV
Subcutaneous
Intranasal
Inhalation
Process by which the drug is removed from the body
Excretion
primary site for drug excretion
Kidneys
What are the organs that facilitate primary excretion?
Kidneys (urine)
Gut (feces)
Skin (sweat)
Lungs (Breath)
Mouth (Saliva)
Extent to which active ingredients are absorbed and transported to site of action
BIOAVAILABILITY
IV administration equates to?
IV administration = higher – 100% bioavailability
PO administration equates to?
PO administration = less – <100% bioavailability
What are the factors of bioavailability?
Drug solubility
Pharmaceutical formulation
pH
Food
Peaks and troughs in plasma levels with other routes of administration, Dose regimes are calculated to maintain therapeutic plasma
Plasma levels
Amount of plasma from which the drug can be totally removed per unit time
DRUG CLEARANCE
The time required for the body to eliminate 50% of the drug
Half life
needs to be given frequently
Short half-life (2-4hrs)
requires less frequent dosing
Long half-life (21-24hrs)
How many half lives are needed to to approx eliminate 98% of a drug from the body?
5-6
time in which the plasma concentration falls by 1/2
Plasma half life
time in which a pharmacological effect of a drug, and any of the active metabolites, has declined by 1/2
Biological effect half life
time in which the total amount of drug in the body after equilibrium of plasma with other compartments (fat and muscle) is halved
Biological half life
Plateau concentration is also known as?
Steady state concentration
It is the Indication of safety
for a drug
Therapeutic Index / Ratio
Metabolism + Excretion = ?
Elimination
The formulation of the product for each delivery route is vital to ensure optimal activity and consistent delivery
Routes of Administration
absorption is hampered by food, drug may be destroyed or may not be absorbed, first pass metabolism
Oral
Tablets / Capsules / Elixirs /Syrups / Suspensions / Granules / Powders / Caplets / Drops are administered ____
Orally
ID / Subcutaneous / IM / IV / Intra-thecal / Epidural / Spinal / Depot are administered _____
Parenteral
Tablets / Sprays are administered _____
Sublingual / Buccal
no degradation by digestive juices and no first pass metabolism
ublingual / Buccal
Aerosol inhalers / Dry powder inhalers / Nebuliser solutions / Spacers are administered _____
Inhaled
Suppositories / Enemas are administered _____
Rectally (PR)
useful in patients who cannot swallow/vomit/uncooperative
Rectal administration
Pessaries / Creams / Vaginal tablets are administered _____
Vaginally
Creams / Gels / Patches are administered _____
Transdermal
Creams / Lotions / Gels / Nasal sprays / Shampoos / Suppositories / Peccaries are administered _____
Topically
Pills or tablets that are coated with substances which resist the acid juice of the stomach but permit disintegration in intestinal juices
ENTERIC-COATING
Release the active drug over an extended period of time
Sustained release
