Pharmacology Flashcards
What is drug?
Chemical substance (other than food) that when administered to a living organism produces a biological effect on the structure or function of the body.
What are medicinal drugs?
Substances intended for the use of diagnosis, prevention, and treatment of disease.
What are non-medicinal (recreational) drugs?
Includes illegal substances such as cannabis, heroin, cocaine, and legal substances such as caffeine, nicotine, and alcohol.
What are therapeutic effects of drugs?
-Intended/Desired outcome of drug administration
-Seen as beneficial.
What are side effects of drugs?
-Unintended effects
-Known/ predictable
-Usually harmful/negative but occasionally beneficial.
-Does not hinder the primary effect of the drug
What are adverse effects of drugs?
-Undesirable effects
-Undocumented/unpredictable
-More severe/harmful
-Can hinder treatment/cause complications.
Name types of drugs used in dentistry
-Local anaesthetic e.g. Lidocaine, Articaine
Prevent pain during procedures
-Antimicrobials e.g. Penicillin, Fluconazole
Treat and prevent infections
-Anxiolytics e.g. Diazepam, Midazolam
Reduce anxiety
-Analgesics e.g. Paracetamol, Ibuprofen
Reduce postoperative pain
What is pharmacodynamics?
The effects of the drug on the body and mechanism of action.
(What the drug does to the body)
What is pharmacokinetics?
Term to describe the 4 stages of absorption, distribution, metabolism, excretion of drugs.
(What the body does to the drug)
What can drugs do in the body?
Simulate normal body communications,
Interrupt normal body communications
Act on non-host organisms to aid body defences.
What are the components of the autonomic nervous system?
Sympathetic (Adrenaline) and Parasympathetic (Acetylcholine).
What is the role of sympathetic stimulation on heart rate?
Speeds up the heart via Beta-adrenergic receptors.
What is the role of parasympathetic stimulation on heart rate?
Slows the heart via cholinergic receptors.
What are autonomic drugs?
Drugs that enhance or inhibit the function of the sympathetic NS and parasympathetic NS.
Examples of autonomic drugs
Adrenaline (beta agonist)
Atenolol (beta blocker)
Pilocarpine (cholinergic agonist)
Atropine (cholinergic blocker)
Fill in the blank: Drugs can be administered through a variety of _______.
[routes].
Types of drugs administration
-Topical: Drug applied to the tissue where it acts
-Systemic: Drug applied to the whole organism
-Parenteral: Drug administered by injection
-Transdermal: Drug applied to the skin for adsorption
-Subcutaneous: Drug injected into the tissues of the skin
-Intramuscular: Drug injected into muscle
-Intravenous: Drug injected into a vein
-Transmucosal: Drug applied to the mucosa for adsorption
What are the four main modes of action for drugs?
- Activation or blocking of Receptors
- Activating or blocking Enzyme function
- Opening or blocking Ion Channels
- Facilitation or blocking Transport systems
Receptors can be coupled to:
-Ion channels
-G-proteins
-Enzymes
-Gene transcription
What determines drug efficacy?
- Affinity – how avidly the drug binds to the receptor
- Occupancy – how much time the drug spends on the receptor
What is an agonist?
Binds to receptor and initiates the same action that would be produced by the substance that normally binds to the receptor.
What is a partial agonist?
Binds to receptor but only partially activates the receptor, producing less than maximal effect.
What is an antagonist?
Binds to but does not activate the receptor, blocking/reducing response.
What is the difference between competitive and non-competitive antagonists?
- Competitive Antagonist: Binds to the same site on receptor as agonist
- Non-competitive Antagonist: Binds to a different site on receptor and prevents activation
What are enzymes?
Proteins that speed up chemical reactions in the body and remain unchanged at the end of their normal reaction.
How do drugs affect enzyme action?
- Competitive Substrate Antagonism: drug competes with the substrate to bind to the enzyme
- Non-competitive substrate inhibition: drug binds to a different site, causing a conformational change that prevents substrate interaction
What can ion channel effects change?
- Cell electrical activity
- Ion influx
True or False: Agonists bind to receptors and cause an effect.
True
True or False: Antagonists bind to receptors and cause an effect.
False
What is the effect of increasing temperature on enzyme activity?
As temperature increases, enzyme activity increases until optimal temperature, beyond which it becomes denatured.
What are the four stages of pharmacokinetics?
Absorption
Distribution
Metabolism
Excretion
What is the most commonly used route of drug administration?
Oral route
What are the advantages of using oral route as drug administration?
Convenient portable, painless
Non invasive
Cost effective
Patient can self administer
What are the disadvantages of using oral route as drug administration?
Slow onset
May be inefficient- high dose/ low solubility Variable absorption- Food interactions in the GI tract, GI disease, Gastric acid may destroy drug
‘first-pass’ metabolism
Which organ is responsible for first-pass metabolism?
Liver
Why does glyceryl trinitrate (GTN) require a higher dose when taken orally?
It undergoes extensive first-pass metabolism, reducing its bioavailability
What is an example of a drug that is activated by first-pass metabolism?
Valaciclovir → Acyclovir
What is the difference between enteral and parenteral drug administration?
Enteral is via the gut; Parenteral is not via the gut
Give examples of parenteral drug administration.
Intravenous (IV), Intramuscular (IM), Subcutaneous (SC), Transdermal
Which route of administration avoids first-pass metabolism?
Intravenous (IV), Sublingual, Rectal, Transdermal, Inhalation
What are the advantages of using IV & IM as drug administration?
Very rapid onset
Predictable plasma levels
No first pass metabolism
What are the disadvantages of using IV & IM as drug administration?
Allergic reactions more severe
Short duration of action
Requires trained staff to administer
Drug cost higher
Painful
What are the advantages of using Transdermal & Subcutaneous
as drug administration?
No first pass metabolism
Allergic reactions often very localised Prolonged action – can be days with transdermal patches
Can be self administered
What are the disadvantages of using Transdermal & Subcutaneous
as drug administration?
Very slow onset
Drug cost higher
Effect will vary from person to person and site to site
What is bioavailability?
The proportion of an ingested drug that reaches systemic circulation for clinical effect
What factors can affect drug bioavailability?
First-pass metabolism, drug formulation, food interactions, gut absorption
What is drug distribution?
The movement of a drug to and from the blood and various tissues
What protein commonly binds to drugs in the blood?
Albumin
How does plasma protein binding affect drug activity?
Bound drugs are inactive; only free drugs exert effects.
The rate of drug diffusion into tissues depends on:
Blood flow to the area
Membrane characteristics
pH levels
Active secretion into tissues
Models of Drug Distribution
Single Compartment Model – Assumes the drug is evenly distributed throughout the body.
Two Compartment Model – Assumes the drug reaches equilibrium with different tissues at different rates.
Factors Affecting Drug Distribution
Different tissues may receive varying drug concentrations.
Some drugs have a preference for specific tissues.
Lipid-binding drugs (e.g., halothane, isoflurane) can accumulate in tissues, leading to slow release and prolonged effects.
What are the two phases of drug metabolism?
Phase 1 - Modification
(Oxidation, Reduction, Hydrolysis)
Phase 2 - Conjugation
(Glucuronidation, sulphation, methylation, acetylation)
What enzyme system is responsible for drug metabolism in the liver?
Cytochrome P450 system
What are the major routes of drug excretion?
Renal (urine)
Hepatic (bile)
Pulmonary (lungs)
Which three stages are involved in renal drug excretion?
Glomerular filtration
Reabsorption
Secretion
What is plasma half-life (t½)?
The time taken to eliminate half of the drug from the body
What is the difference between first-order and zero-order kinetics?
First-order: Drug elimination is proportional to concentration
Zero-order: Drug elimination occurs at a fixed rate.
Why is paracetamol overdose dangerous?
It produces toxic metabolites that cause liver damage and hepatotoxicity.
Why must drug doses be reduced in renal or liver disease?
Impaired metabolism/excretion can lead to drug accumulation and toxicity.
Which drug interactions occur due to competitive plasma protein binding?
Warfarin & Aspirin
Why is intravenous administration preferred for emergency situations?
Rapid onset, predictable plasma levels, bypasses first-pass metabolism.)
What are the possible hazards of drug administration?
Allergy, drug interactions, acute toxic reactions, and death.
What is an unintended effect of drug administration called?
Side effect.
How does the BNF categorize side effects?
Common, uncommon, rare, very rare, and frequency unknown.
What is the difference between a mild allergic reaction and anaphylaxis?
Mild allergies cause rashes, itching, and sneezing
Anaphylaxis is a life-threatening reaction requiring urgent treatment with adrenaline.
What is a drug interaction?
A reaction between two or more drugs, or between drugs and food/supplements, affecting drug action or causing side effects.
Give an example of drug interaction due to protein binding.
Warfarin & aspirin/NSAIDs.
What factors determine drug toxicity?
Chemical structure, absorption, metabolism, and elimination capacity of the body.
What are key principles of safe prescribing?
Treat the whole person, prescribe only when necessary, justify drug use, and consider risk vs benefit.
Why should dentists review a patient’s medical history before prescribing?
To avoid contraindications, drug interactions, and dosage adjustments for conditions like liver/kidney disease.
What is the role of the British National Formulary (BNF)?
It provides guidance on drug prescribing, dosage, side effects, and interactions.
What is the Dental Practitioners’ Formulary (DPF)?
A guide for drug management in dental and oral conditions, used by NHS dentists.
What details must a prescription include?
Patient’s full name, age (if under 12), date, prescriber’s details, drug name, dosage, frequency, quantity, and signature.
Why must prescription pads be kept secure?
To prevent misuse or theft.
What considerations should be made when prescribing for children?
Age-appropriate dosage and sugar-free formulations (marked as “SF”).
What should patients do if they experience unexpected drug reactions?
Stop taking the drug and contact the prescriber immediately.
What is the most common dental prescribing error?
Prescribing the wrong drug.
How can prescribing errors be minimized?
Double-checking the BNF, reviewing medical history, and ensuring correct prescription form completion.
Where can dentists access the latest drug prescribing guidelines?
On the SDCEP Drug Prescribing for Dentistry website.
