2. Pharmacodynamics Flashcards
Define “Pharmacology”
the study of drugs; what they are, what they do, and how they do it
Define “Therapeutics”
the application of pharmacology to the treatment or prevention of disease
Where do drugs come from?
- plants
- minerals, ex. Ca2+
- synthetic
- animals, ex. pregnant mare urine = Premarin
Explain drug nomenclature
- Drugs have different names depending on who is communicating
- Chemists and basic researchers may use the drug’s chemical name
- Based on standardized naming according to structure
- Regulatory body assign a generic (nonproprietary) name through clinical trials
- Usually suffixed with like drugs to indicate mechanism of action (e.g. lidocaine, procaine)
- May vary by country (e.g. acetaminophen/paracetamol)
- Chemists and basic researchers may use the drug’s chemical name
- Manufacturer assigns a brand (trademark) name under which they will market
- Often strategically designed to aid in marketing/public perception
- drugs may also have a street name, pr a slang term used in reference; this is most common with illicit drugs or drugs of abuse
–> ex. (this is the same drug):
- chemical name: acetylsalicylic acid
- generic name: aspirin
- brand name: St. Joseph aspirin
What are Generic name and Brand name?
- Brand Name
- The first version of a drug to be sold in a country
- Company has funded all stages of pre-clinical and clinical development
- Expensive process; expectation of revenue generation
- Protected by patent for ~20 years from time of discovery
- means other companies cannot sell it
- Generic Name
- A copy of the brand name drug that can be manufactured and sold by any company, following patent expiry
- Fewer studies needed and easier to gain regulatory approval if used for the same purpose
What is the identical and different between Generic vs Brand name?
- Identical
- Health Canada Approval process
- Mechanism of action
- Active ingredients, and amount
- Safety
- Efficacy (including time to onset)
- Different
- Cost; generics are cheaper
- Companies do not need to recoup as many costs
- Economics: supply & demand
- Excipients (non-medicinal ingredients)
- Color, flavor, size, appearance
- Cost; generics are cheaper
Choosing between Brand name and Generic. Prescription vs OTC drugs.
- Prescription drugs
- Most insurance policies cover generic drugs if available
- Pharmacies automatically substitute generic equivalents
- Physician can specifically order “no substitution”
- Over-the-Counter drugs
- Consumers have free choice
- Brand name companies hope for loyalty and/or success from advertising
What are the 2 branches of pharmacology? Explain.
- Pharmacodynamics
- “What the drug does to the body”
- Effect(s) of drug on body processes
- Pharmacokinetics
- “What the body does to the drug”
- Movement and fate of drug in body
- ex. processes that guide the breakdown of the drug
What is different and what is the same in PD and PK?
- Pharmacokinetics
- Dosage Regimen
- How much? How often? For how long?
- Dosage Regimen
- Both PD and PK:
- drug in blood
- drug at target receptors
- Pharmacodynamics
- Pharmacological effects
- Know the [ ]
Define “drug”
- a chemical substance that alters the function of a biological system
- includes normal body constituents
- beneficial or detrimental
Define “receptor” and what structures can it be?
- Chemical entity (usually protein) that binds
drugs - Transmembrane or intracellular
- Specialized receptors
- Generalized receptors
- Enzymes, nucleic acids, protein complexes, etc.
Explain the Drug-Receptor Theory. Define Affinity as well as Intrinsic efficacy and show how it applies to the theory.
Drug (D) + Receptor (R) ⇌ DR ⇌ DR* —> Effect
- Affinity
- Measure of how tightly drug binds to receptor, based on complementary structures
- “Will key fit in lock”
- *applies between the R and DR in the model above
- Measure of how tightly drug binds to receptor, based on complementary structures
- Intrinsic efficacy
- Dependent on the drug’s structure
- Chemical moieties that allow binding to elicit a response
- “Will key turn”
- applies between the DR and DR in the model above
What are some (drug) exceptions to the Drug-Receptor Theory?
- Some drugs do not require receptors to work
- Antacids – act by chemical reaction, neutralizing stomach acid in the stomach
- Osmotic diuretics – promote urine excretion by altering water flow in the kidney
- Some antibiotics, antiviral drugs, and anticancer drugs
- Generally act by disrupting structural/functional aspects of the cell
- ex. cell membrane/wall integrity, nucleic acid production
How does the Drug-Receptor Complex come together?
- Chemical bonds in the active (binding) site lead to the formation of the transient (temporary) drug-receptor complex
- Drug shape and affinity for the receptor binding pocket are important for dictating the number and strength of these collective bonds
- Unbound drug exists in equilibrium with the receptor-bound drug
explain the specificity/Selectivity of drug and receptors.
- Drug property relating to its ability to bind to a particular type of receptor, above and beyond any other receptor type
- Drugs that more selectively bind fewer receptor types (or only a single type!) are said to have higher specificity
- Non-specific/non-selective drugs tend to have more side effects than specific/selective drugs
