Week 1 Flashcards
What is a drug?
different types of drugs
- A substance that act on living systems at the molecular, cellular or whole body level that can provoke changes in body function or mood
- Generally considered to the be active ingredient of a medicine
- Key point is that drugs have specificity
o A non-specific drug would be useless! - Plant derived:
o Morphine, cannabis, aspirin - Animal derived (pigs, cows):
o Insulin, pancreatic enzymes - Synthetic compounds are preferred though due to:
o Better control of product variability
o Cheaper to make (automation)
o Manipulate parent compounds to make them more effective
What is pharmacology?
- The study of the interaction of chemicals (drugs) with living systems
What is clinical pharmacology
- The scientific study of drug effects in humans
What is pharmacy
- The profession of preparation and supply of medicines
- Usually the main point of contact regarding drug information
What are therapeutics
- The branch of medicine concerned with the treatment of disease
What is toxicology?
- The study of the undesirable effects of chemical agents (poisons) on living systems
- Also includes the actions of industrial pollutants, natural organic and inorganic poisons and other chemicals on the ecosystems and species
What is a drug receptor?
- The molecular components of the body with which a drug interacts to bring about its effects
- Receptors are generally proteins located on cell outer membranes
- They are targets for drug molecules in the body, each receptor is specific for a particular drug
What is pharmodynamics?
- The fundamental actions of a drug on the body at a physiological, biochemical or molecular level
- Includes receptor interactions, dose-response phenomena, and mechanisms of therapeutic and toxic action
o Essentially how drugs work!
Pharmokinetics
- The actions of the body on a drug
- Includes: ADME
o Absorption
o Distribution
o Metabolism
o Excretion
Pharmacogenetics
- The study of the relationship between genetic factors and variations in drug response
Nature of the Drugs At room temp drugs may be? give ex Size and molecular weight? Selectivity pf a drug depends on? Drug receptor bonds?
- At room temp drugs may be: o Solid – asprin, nicotine o Liquid – ethanol, atropine o Gaseous – nitrous oxide - Size and molecular weight o Can range 7 (lithium) to 50,000 (thrombolytic enzymes-alteplase) o Majority of drugs between 100 and 1000 - Selectivity of a drug depends on: o The chemical nature of the drug o The dose given and the route by which it is administered o Special features of the recipient • Genetic makeup • Sex • Age • Co-existing disease - Drug-receptor bonds: o Drugs bind to receptors with a variety of chemical bonds • Very strong covalent (irreversible) • Weaker electrostatic (between cation and anion) • Very weak interactions (hydrogen, van der Waals + hydrophobic)
Effects produced by drugs and body
Psychosocial influences of medication include?
- Chemical interaction between the drug and body
- Psycho-social influences of the medication including:
o Placebo: form of medication that doesn’t contain any drug
o Mood: act of taking a pill and feeling better
o Expectation: yours and your GPs
o Imagination: advertising, friends, recommendation
If a drug ends in_____ what is its classification and prototype for class?
- -olol
- -caine
- -dipine
- -tidine
- -prazole
- -quine
- -ane
- -zosin
- -profen
- -clovir
- -mycin
- -cycline
- -zepam
- olol- beta blocker eg propranolol
- caine- local anaesthetic e.g. cocaine, procaine
- dipine- DHP Ca Channel blocker eg Nifedipine
- tidine- H2 receptor antagonist eg Cimetidine
- Prazole- protone pump inhibitor eg Omeprazole
- quine- Antimalarials eg Chloroquine
- Ane- halogenated anaesthetics e.g. Halothane
- zosin- alpha adrenergic blockers eg prazosin
- profen - NSAIDS eg Ibuprofen
- Clovir- ANtivirals eg Acyclovir
- Mycin- Macrolide antibiotics eg Erythromycin
- Cycline- broad spectrum antibiotics e.g. tetracycline
- Zepam- BDZ sedatives eg Diazepam
What is all the info needed to compile a drug profile?
- Pharamacology:
o The molecular action of the drug including its pharmacodynamics and pharmacokinetics (ADME) - Clinical trials:
o These aim to measure the therapeutic effectiveness of the drug - Indications:
o A particular illness or disease state that the drug has been shown to have a therapeutic effect - Contra-indications:
o A specific illness or disease state in which a drug should NOT be used, because it is harmful to the patient - Precautions:
o A disease state in which a drug should be used with care because it MAY be harmful to the patient - Interactions:
o A list of other drugs which may interact with the drug of choice, interfering with its pharmacodynamics or pharmacokinetic properties - Adverse reactions:
o Any side effects caused specifically by administration of a drug - Dosage and administraton:
o The amount and frequency of a drug taken per day and normal routes of administration - Overdose:
o Information on overdosage amounts, symptoms and treatment - Pack and storage:
o Information on proprietary pack sizes and storage conditions
What are the different types of drugs with respect to the sympathetic (adrenergic) NS?
- Drugs can be biological in origin → Noradrenaline + adrenaline
- Non-biological in origin → Clenbutarol (beta agonist) –mimic the effect of adrenalin etc and induces smooth muscles relaxation
- Drugs which block biological processes→ propanol (beta blocker), atenolol (beta-adrenergic blocking agents, are medications that reduce your blood pressure. Beta blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline. When you take beta blockers, the heart beats more slowly and with less force)
- Drugs which enhance biological processes→ Salbutamol (bata agonist)- activates beta-receptor- combats asthma, opens airways.
Whats a ligand?
Any molecule that binds with another molecule, eg agonist, antagonist, drugs etc
Whats an agonist?
Substance which acts as a receptor to initiate a response- eg adrenaline- changes heart physiology (+’ve effect) or could have an agonist that slows HR down.
Antagonist
Substance that binds to the receptor without causing activation- compound which blocks effects of agonist.
To compare different drugs you can either:
- Measure response of a drug on an appropriate biological medium
- Calculate the actual amount of drug that binds to specific receptor sites.
What is the graded-dose response?
• Used when response of a particular system is measured against increasing concentrations of a drug. (continuous measure) eg smooth muscle contraction, BP, urine production rate, etc.
• Can be used to work out effective doses
• Effective dose estimates frequencies that each dose elicits in the population.
• Experiments are often performed on a blood vessel as they have many target receptors and effects can be measured relevant to various pathophysiological conditions.
Emax
what is the Emax?
Maximum effect drug has on system
What is EC50
Concentration of drug that will elicit 50% of maximal effect
What is the quantal dose-response?
Response is all or nothing (either conscious or unconscious, seizue/no seizure, live/dead)
• Used to work out lethal doses eg LD50 dose which kills 50% of the population
What is the Therapeutic Index (TI) ? How do you calculate it?
(also referred to as therapeutic window or safety window or sometimes as therapeutic ratio) is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes toxicity.
TI= LD50/ ED50
LD-lethal dose
Efficacy:
The effect of the drug (Strength). Antagonist = 0 effect as they don’t activate receptors, just blocks other substances from having their effect.
Potency
The dose of drug required to produce given effect
What is biological specificity?
Compound must bind to, and act on, only certain cells and tissues. Eg Histamine causes bronchial & vasc. Smooh muscle- HIGH biological specificity. Ethanol has similar effects on most cells and tissues (LOW biological specificity)
Chemical Specificity
Effect of changes in the chemical structure of a drug on pharmacological activity. Eg imidazole to pyrrazole- high chemical specificity. Ethanol- low chemical specificity
What could possible harmful effects of drugs be?
- Overdose
- Increased sensitivity
- Lack of selectivity
- Drug allergy
- Cutaneous reactions
- Drug toxicity in pregnancy and lactation
Harmful effects
Overdose?
o When a drug is administers in a higher dose than required for its therapeutic effect
o Can affect body function directly or indirectly
o Therapeutic index determines the safe level of the drug and the lethal level of the drug
Harmful effects
Increased sensitivity?
o Certain body functions can develop hypersensitivity to particular drugs that result in unwanted effects at normal doses
• Eg. Morphine in patients with chronic lung disease
Harmful effects?
Lack of sensitivity
o Can occur when despite proper dosing and normal sensitivity, undesired effects occur due to a loss of specific effects at the target organ
• Eg. Atropine: only acts at one type of receptor (muscarinic acetocholine) which are located throughout the body. This lack of specificity can be overcome with local administration (to the eye only)
Drug Allergy
o The immune system normally functions to remove high molecular weight foreign material taken up by the host. The use of animal materials such as pig insulin etc. has resulted in a number of allergic reactions
o 4 such drug allergic reactions have been noted:
• Type 1 reactions:
• Anaphylactic shock
• Hypotension
• Asthma
• Urticarial
- Type 2 reactions:
- Haemolytic anaemia
- Agranulocytosis
- Thrombocytopaenia
- Type 3 reactions:
- Inflammation resulting in fever, arthritis and neuropathy
- Type 4 reactions:
- Contact dermatitis
Harmful effects
Cutaneous reactions
o Systemic distribution of many drugs can result in skin reactions caused by photosensitisation of the drug
o Can be harmless or lethal
o Common occurrence with antibiotics and NSAIDs
o They include:
• Toxic erythema
• Rash similar to measles
• Urticaria
• Itchy swelling arising from an anaphylactic shock
• Fixed eruptions (drug exanthemas)
• Few, localised painful lesions that will reappear at the same spot with repeated drug exposure
• Toxic epidermal necrosis (TEN)
• Death of skin keratinocytes and the detachment of the epidermis from the dermis
• Lethal if over 30% of the body affected
Harmful effects
Drug toxicity in pregnancy and lactation.
2 categories
o Major group involved in drug reactions!
o Drugs taken by the mother can be passed on transplacentally or via breast milk
o 2 categories:
• Predictable effects that derive from the known pharmacological properties of the drug
• Eg. Beta- blockers can cause masculinisation of female fetus by androgenic hormones and bradycardia
• Drug effects that specifically affect the fetus (teratogenicity) and cannot be predicted based on pharmacology
• Eg. Thalidomide which can cause limb malformation
o Probable risk assessment for drugs during pregnancy should include:
• Time of drug use
• Ability to cross placenta
• Teratogenicity
