pharmacology

STAT

Immediately

AC

before food

BD

twice daily

OD

Every day

OM

Every morning

ON

Every night

PC

After food

PRN

As needed or as required

QDS

4 times a day

TDS

3 times a day

definition of pharmacology

The study of actions, mechanisms, uses and adverse effects of drugs

medicinal drugs

Substances used to diagnose, treat, or prevent disease.

nonmedical drugs

Substances used recreationally can be illegal or for everyday use .

pharmacodynamics

what drugs do to the body

Statins

• Work by slowing down the production of LDL-cholesterol in liver by blocking enzyme called HMG-CoA-reductase

• Offered if you have too much bad cholesterol in blood - it takes it out of blood to make bile so levels are lowered

• Statins can lower triglycerides - high levels is linked to liver disease, heart disease and diabetes

• Can raise HDL cholesterol (good) which can help clear fat from arteries

Levothyroxine

• Used to treat underactive thyroid gland (hypothyroidism) and prevents symptoms

• Thyroid gland makes hormones which help control energy levels and growth

• Is taken to replace thyroxine (hormone)

• Only available on prescription - tablets or as liquid

omeprazole

• inhibits (reduces) the amount of acid your stomach makes

• used to treat indigestion, heart burn, acid reflux and stomach ulcers

• called a proton pump inhibitor - It works by blocking the proton pump in the stomach lining.

• prevents protein pumps from working properly, which reduces the amount of acid produced, alleviating symptoms associated with excess stomach acid.

Amlodipine

• used to treat high blood pressure which can prevent heart disease, heart attacks and strokes and ease angina

• calcium channel blocker - prevent calcium from entering the cells of heart muscle and blood vessels, leading to relaxation and dilation, which lowers blood pressure (as calcium constricts)

pharmacokinetics

what body does to the drugs

Stages of ADME

• A - ABSORPTION

• D - DISTRIBUTION

• M - METABOLISM

• E - EXCRETED

Absorption

It is the process by which a drug enters the bloodstream from its site of administration.

paternal/enteral

determined by

• the physical nature of dosage form

• the presence of food in stomach

• the composition of gastrointestinal contents

• the gastric or intestinal PH

• mesenteric blood flow

• concurrent administrations with other drugs

Distribution

• Process of the drug getting where it needs to be -

• typically via blood stream, which transports drug and binds plasma proteins

• Dosage and timing will affect concentration in bloodstream as does ROA

metabolism

• Dissolve in gastric fluid and diffuse across membranes

• The higher the solubility of lipids the more rapidly the drug will diffuse into tissues

• The main site is the LIVER but can also happen in – lungs, kidneys, blood and intestines

first pass metabolism

• drug taken orally is metabolized by the liver before reaching the rest of the body.

• Absorption from the intestines, the drug enters the hepatic portal vein, which carries it directly to the liver—where much of it may be broken down—reducing how much of the active drug enters the bloodstream.

Excretion

• kidneys - remove toxins from bloodstream

• Ageing kidney - slows down and becomes less efficient, important to consider when prescribing

• Estimated Globular Filtration Rate - test used to assess kidney function by estimating how much blood is filtered by kidney per min

safe dose

The maximum amount of a drug that can be administered without causing harm to the patient. This is determined by factors such as age, weight, and organ function.

can cause severe side effects and toxicity

half life

The time it takes for the concentration of a drug in the bloodstream to be reduced by half impacts dosing frequency and duration of effect.

short half-life - more withdrawal problems

long half-life - fewer problems

pros of oral administration

• easy and cheap

• convenient

• low infection risk

• painless

cons of oral administration

• exposed to GI tract

• first-pass metabolism - Low bio

• loss through vomiting

pros of intravenous administration

• fast

• avoids GI exposure

• avoids first past (increase bioavailability)

cons of intravenous administration

• non reversible

• infection risk

• pain/fear factor

• need training

bioavailability

the proportion of a drug that enters the circulation when introduced into the body and is available for action.

• Oral medication - low bioavailability - drug is waster/lost in stomach - why oral have regular dosage

• IV medication - 100% bioavailability, not affected or damaged by stomach, immediately enters systematic circulation, works quickly

A - Enteral

absorption via GI tract/small intestine (oral, buccal and sublingual)

kidney failure

• eGFR gives you stages 1 to 5

• normal (stage 1) = above 90ml/min but other tests have detected kidney damage

• lost all function (stage 5) - below 15ml

A - parenteral

avoids the GI pathways (IM, IV subcutaneuous)

Pharmacovigilance

safety of drugs – characterisation, detection and understanding of ADR’s