Pharmacology Flashcards
What is the definition of pharmacology?
The study of the way living systems are affected by chemical agents
What is the definition of a drug?
Any chemical agent that affects a biological system
What is the definition of a receptor?
A protein that has a specific binding site to a ligand
Explain how the dose response curve work?
More dose = greater response
But once all receptors are occupied, the response plateaus
Log graph has sigmoid curve
What is the definition of EC50?
The dose needed to create a 50% response from the system
If a drug has a higher affinity to the receptor, how does the EC50 change?
It shifts to the left
What is the definition of affinity?
Determined the strength of chemical attraction between the drug and receptor
A lower EC50 indicates a higher affinity
What is the definition of efficacy?
Determined by how good the drug is at activating the receptor?
What responses can occur from ligand binding?
Full response
Partial response
No response
What is the affinity and efficacy for a full agonist?
High affinity and high efficacy
What is the affinity and efficacy for a partial agonist?q
High affinity and lower efficacy
What is the affinity and efficacy for an antagonist?
High affinity and no efficacy
What is the definition of an agonist?
Mimic normal effect of receptor
What is the definition of an antagonist?
Block normal effect of receptor
Explain why the dose response curve shifts to the right with added antagonist?
The antagonist completes for the binding site, and so more agonist is needed to activate the desired response
What are the enteral routes for a drug?
Oral
What are the parenteral routes for a drug?
IV IM Subcutaneous Transdermal Inhalation
What are the advantages and disadvantages for oral administration?
Adv - socially acceptable Dis: - slow onset - variable absorption - gastric acid may destroy drug - first-pass metabolism
Explain First Pass metabolism?
All blood from the GI drains to the hepatic portal vein
Hepatic portal vein drains to the liver
Drugs only reach systemic circulation after passing through the liver
What are the advantages and disadvantages for non-oral drug administration?
Adv: - predictable plasma levels - no first pass metabolism Dis: - allergic reactions more severe - access difficulties - higher cost
What is a solution to first pass metabolism?
Higher dose
Name the 5 factors which affect oral absorption?
Lipid solubility and ionisation Drug formulation GI mobility Interactions with other substances in the gut GU tract disease
What is the definition of bioavaliability?
Proportion of an ingested drug that is available for clinical effect
What can alter a drug’s bioavailability?
Dosage form
Destruction in the gut
Poor absorption
First pass metabolism
What is the definition of volume of distribution?
How much of the body the drug is diluted in
Name the 2 forms of drug transport binding?
Lipid
Plasma proteins
What are the phase I reactions for drug metabolism?
Oxidation, reduction and hydrolysis
What are the phase II reactions for drug metabolism?
Glucuronidation, sulphation, methylation, acetylation and glutathione
Name the 5 forms of drug excretion?
Urine Bile Exhalation Sweat Saliva
How can disease affect drug metabolism?
Reduced ability to metabolism, higher concentration, need lower dose
Name the 2 pathways for drug metabolism?
Zero-order kinetics
First-order kinetics
What is the definition of zero-order kinetics?
Removal of a fixed amount over a specific amount of time
What is the definition of first-order kinetics?
Drug eliminated in proportion to its concentration in the body
What can dosing too frequently cause?
Toxicity, depending on drug’s therapeutic index
What can dosing too infrequently cause?
Sub-therapeutic plasma levels, giving no clinical effect
Name 4 examples of possible side effects for all medications?
Allergy
Anaphylaxis
Drug-drug interactions
Acute toxic reactions
What is the definition of drug-drug interactions?
One drug interferes with the absorption, action or metabolism of another
What can occur from an acute toxic reaction?
Bone marrow suppression
Hepatotoxicity
Biliary stasis
Acute nephrotoxicity
What must a full prescription contain? MUST BE CLEAR
Name, address and age DoB or CHI number Number of treatment days The drug Drug formulation and dose Instructions on quantity to be dispensed Instructions for the patient Signed
How long are prescriptions available?
6 months
How many dispensing occasions can be present?
Many
Time saver
What to avoid when writing a prescription?
Abbreviations
What is some specific advice to give to patient after prescribing a drug?
Take drugs at correct time and finish the course
Not feeling well - STOP
Side effects should be discussed/interactions
Keep medicines away from children
What to consider about the patient’s medical history before prescribing a drug?
Current medical issues
Chronic medical issues
Current medication list
Previous adverse reactions
What is the definition of polypharmacy?
Where 4 or more drugs are prescribed for the patient
What drug interactions does Warfarin have?
ALL drugs possible Systemic antifungals and miconazole
Erythromycin, metronidazole and amoxycillin
ALL NSAIDs
What drug interactions do statins have?
Systemic antifungals
What are the 5 main drug categories a dentist can prescribe?
Antibiotics Antifungal Antiviral Analgesics Hypnotics
Name 2 topical antifungals?
Nystatin
Miconazole
Name 2 systemic antifungals?
Fluconazole
Itraconazole
What is the formulation for nystatin?
Suspension
Ointment
What is the formulation for miconazole?
Gel
Buccal adhesive tablet
Cream and ointment (+hydrocortisone)
what is the formulation for fluconazole and itraconazole?
Capsule
Suspension
Name 2 antivirals?
Aciclovir
Peniciclovir
WHat is the formulation for aciclovir?
Topical cream
Systemic
What are the indications for aciclovir?
HSV or Zoster (herpes)
Prophylactically (herpes)
What is the formulation for penciclovir?
Cream
Name 5 analgesics a dentist can prescribe?
Paracetamol Aspirin Co Codamol (can't prescribe) Ibuprofen Diclofenac
What is the function of paracetamol?
Antipyretic and analgesic
Little anti-inflamm properties
Few sides
Combined with codeine
Name 3 COX I inhibitors? ad their deriv?
Aspirin - salicylates
Ibuprofen - propionic acid deriv
Diclofenac - phenylacetic acid deriv
When to avoid aspirin?
In children
Dosage for ibuprofen?
200-600 three times daily, depending on situation
What is the function of diclofenac? and its dose?
More effective anti-inflammatory
50mg 3 times a day
Name 4 types of anxiolytics?
Diazepam*
Temazepam
Nitrazepam
Promethazine
Name 2 topical antiseptics?
Chlorhexidine
H202
Name 2 topical analgesics?
Benzamine spray or m/w
Lidocaine spray/ointment
Name 4 topical immunomodulators?
Beclomethasone inhaler
betamethasone risne
Hydrocortisone pellets
Doxycycline dispersible tablets
Indications for oral soft tissue infection?
Topical antiseptic
Topical analgesic
Indications for oral mucosal ulceration?
Topical immunomodulator
Topical analgesic
Treatment for dry mouth?
Saliva orthana (spray or lozenge)
Salivix pastilles
Saliva stimulating tablets
Secondary treatments for dry mouth
Higher Fl toothpaste
High caries watch
What alternative to antibiotics can a dentist do for an abscess
Drainage
Name the 5 most common antibiotics prescribed?
Penicillin Amoxycillin Erythromycin Doxycycline Metronidazole
What is the definition of an adverse drug reaction?
An unwanted or harmful reaction which occurs after admin of a drug or drugs and is suspected or known to be due to the drugs
How do ADR affect the NHS?
5% GP consultations
10-20% of hospital in-patients
7% of all hospital admissions
Name the 4 most common ADR drugs?
Aspirin
Diuretics
Warfarin
NSAIDs
How much do ADRs cost to the NHS?
£466 million
Name the 2 main types of ADRs?
Augmented
Bizarre
What is the definition of an augmented ADR?
Predictable from the known pharmacology of the drug: - exagg of intended effect - unrelated to intended therapeutic effect E.g. - hypo with antihyper - dehydrated with diuretics - hyponat with thiazides - breathless with beta-block
Name 2 factors which increases the risk for augmented ADRs?
Drug concentration Patient factors (hepatic enzymes)
Name 3 ways in which to deal with augmented ADRs?
Reduce dose
Try an alternative agent
Treat ADR
Name 3 drugs that cause liver impairment via augmented ADRs
NSAIDs
Warfarin
Metformin
Name 2 drugs that cause heart failure via augmented ADRs
NSAIDs
Glitazone
Name 3 drugs that cause frailty via augmented ADRs
NSAIDs
Sedatives
Antichol
Name 3 drugs that cause dehydration via augmented ADRs
NSAIDs
ACE/ARBs
Diuretics
Name 6 drugs that cause renal impairment via augmented ADRs
NSAIDs ACE/ARBs Metformin Digoxin Antibiotics Opiates
What is the definition of a bizarre ADR?
Not dose related and are not predictable from the pharmacological action of the drug. They are mostly due to specific immune or genetic factors of the patient and therefore cannot be predicted
Give 1 example of a bizarre ADR?
Penicillin allergy;
- some sulphonylureas and acute intermittent porphyria in susceptible people
- Steven-Johnson syndrome with a number of drugs.
Name 2 forms of management for bizarre ADRs?
Stop causative agent
Deal with the ADR
Name the 3 secondary types of ADRs?
Chronic
Delayed
End of use
What is the definition of a chronic ADR?
Predictable from known pharmacology:
- require prolonged period of exposure to develop
Give 2 examples of chronic ADRs?
Osteonecrosis from bisphosphonates
Osteoporosis from high dose steroids
What are the 2 forms of management for chronic ADRs?
Use prophylaxis
Monitoring patients
What is the definition of a delayed ADR?
Effects do not arise until a prolonged period after exposure possible even after drug has been withdrawn
Give 1 example of a delayed ADR?
Chemo:
- increased risk of lymphomas
What is the definition of an end of use ADR?
Effects seen on medicines withdrawal also known as withdrawal reactions
Give 3 examples of end of use ADRs?
Opiates
SSRI
Beta blockers
What is the definition of pharmacovigilance?
Process involving detection, assessment, understanding and prevention of ADRs
Provides continual assessment of the risk and benefits for each drug resulting in the best drug therapy for the patient
Give 1 example of a pharmacovigilance system in the UK?
Yellow card
What information does the Yellow Card system works?
The Scheme collects information on suspected problems or incidents involving:
- side effects (also known as adverse drug reactions or ADRs);
- medical device adverse incidents;
- defective medicines (those that are not of an acceptable quality);
- counterfeit or fake medicines or medical devices;
- safety concerns, e.g. for e-cigarettes or their refill containers (e-liquids).
How does the Yellow Card system work in the UK?
Voluntary scheme
Both healthcare
professionals and members of the public can file a yellow card report.
Healthcare professionals should report all suspected adverse reactions to:
- new drug and vaccines on market and black triangle drug
- children (Mostly off license)
- Serious ADRs for established drugs and vaccines, e.g. anaphylaxis, events that have led to significant harm, those which are fatal.
Name the 3 essential pieces of information included in a Yellow Card report?
Side effect
Info about person
Name of medicine
Name and full address
What is the definition of a drug interaction?
Effects of a drug are changed by the co-admin of another drug
Name the 3 mechanisms that cause drugs to interact?
Pharmaceutical interactions
Pharmacodynamic interactions
Pharmacokinetic interactions
What is the definition of a pharmaceutical drug interaction?
Chemical reaction between drugs prior to admin of dru
Drugs are mixed inappropriately in syringes if infusion fluids before admin
(Phenytoin and glucose)
What is the definition of a pharmacodynamic drug interaction?
Drug B increases/decreases the effect of Drug A without affecting the concentration of Drug A at its site of action
What are the risk factors which cause pharmacodynamic drug interactions?
Acting on same receptor system
Acting at different receptor in same physiological system
Synergistics effects
Antagonists
What is the definition of a pharmacokinetic drug interaction?
Occurs when one drugs affects the absorption distribution, metabolism and excretion of another
Drug B increases/decreases the effect of Drug A by changing Drug A’s concentration at its site of action
Name the 4 stages at which pharmacokinetic interactions can occur?
Absorption
Distribution
Metabolism
Excretion
Describe how absorption of a drug can be affected?
Change in pH
Chelation
Motility
(Occur in SI)
Describe how distribution of a drug can be affected by another drug?
Carried in plasma attached to proteins (albumin)
Active from of drug not protein bound
If drug A displaces drug B from the carrier protein then there is an increase in the active form drug B
Amiodarone displaces digoxin and can lead to toxicity
Describe how metabolism of a drug can be affected by another drug?
Drug A induces/inhibits the enzyme that metabolises Drug B
Warfarin meta inhibited by amiodarone, leading to an increased effect from Warfarin
What is the definition of P450?
Microsomal enzyme found in Liver and Gut
3A4 accounts for 50% of drug metabolism
Also 2D6 important
Name 9 inhibitors of P450?
Omeprazole Disulfiram Erythromycin Valproate Isoniazid Ciprofloxacin and Cimetidine Ethanol (acutely) Sulphonamides Grapefruit juice
Name 6 inducers of P450?
Alcohol (chronic use) Barbiturates Carbamazepine Phenytoin Rifampicin Sulphonylureas
Name 4 drugs that are excreted in their active form via the kidneys?
Methotrexate – NSAIDs increase the risk of methotrexate toxicity because of competition for renal tubular excretion.
Lithium
Digoxin
Gentamicin – can reduce GFR (especially if through levels are elevated), leading to its accumulation as well as a number of other drugs that depend on renal excretion.
How to avoid drug interactions?
Most serious DDIs related to common prescribed drugs are predictable – combination of awareness and use of good reference resources helps when prescribing.
Polypharmacy – major cause of increased risk for DDIs. Prescribers must take responsibility for assessing the risks for individual patients.
Medicines reconciliation, review and de-prescribing can further reduce the risks.
Comprehensive drug histories are vital
Reporting of all ADRs suspected of being related to a DDI
Should you omit Vit K antagonist before extraction?
Check INR, ideally no more than 24 hrs before procedure (up to 72 hrs if patient well anticoagulated). If INR is below 4:
Treat without interrupting medication
Should you omit antiplatelet drugs before extraction?
Aspirin alone:
- treat without interrupting medication (use haemostatic measures)
Clopidogrel/dipyridamole or ticagrelor + aspirin:
- treat without interrupting medication (suturing and packing)
Should you omit NOACs before extraction
Low bleeding risk:
- treat without interrupting medication
Higher bleeding risk:
- advise to miss/delay morning dose (suture and pack)
What is the schedule change for apixaban/dabigatran before high bleeding risk procedure?
Miss morning dose
Then continue as normal
What is the schedule change for rivaroxaban before high bleeding risk procedure?
Delay morning dose:
- take post-treatment dose after 4 hours after haemostasis achieved
