Pharmacology


Pharmacology - the study of drugs and their effects on living organisms

  • Requires basic understanding of anatomy and physiology, chemistry, pathology.

  • 2 Branches of Pharmacology (Pharmacodynamics, Pharmacokinetics) 


Clinical Pharmacology - The study of how drugs work in the human body


Pharmacokinetics - How drugs move into, through and out of the body. 

  • 4 components (ADME) Absorption, Distribution,  Metabolism, and Excretion 


Absorption - The process of drugs entering the body into the bloodstream 

Distribution - The process of where the drug is distributed or dispersed throughout the body. 

Metabolism - The process where the drug is broken down by the body, usually in the liver or gastrointestinal (GI) tract) this results in metabolites which can be inactive or active. 

Excretion - After metabolism the drug is eliminated from the body. 


Bioavailability - the amount of the administered drug that reaches the blood circulation and can be used by the body 

  • Ex. Directly into the vein = 100% effective | Orally = reduced (goes through digestive tract) 

  • 2 Drugs with the same bioavailability = bioequivalence (BE) 


Bioequivalence - the drugs are absorbed equally into the body 

  

Description

Administrative Route 

Abbreviation (if any)

By mouth

oral

PO

Under there tongue 

Sublingual 

SL

Between the gums and cheek

Buccal 

N/A

Into the Muscle 

Intramuscular 

IM

Under the Skin

Subcutaneous 

SC

Into the Vein

Intravenous 

IV

Into the Spinal Cord Spaces

Intrathecal 

N/A

Into the Rectum

Rectal 

PR

Into the Vagina

Vaginal

PV

Through the Skin

Transdermal

N/A

On the Skin

Topical

N/A

Into the Nostril

Intranasal 

N/A

Into the lungs

Inhalation

N/A

Into the Ear

Otic

AS (left ear) AD (right ear)
AU (both ears)

Into the Eye

Ocular or Ophthalmic 

OS (left eye), OD (right eye), OU (both)


Pharmacodynamics -  the study of biochemical and physiological effects of a drug on the body. 

  • Helps us learn what the optimum dose of a drug should be 

  • Limits side effects while maximizing the clinical effects of the drug 

  • For the drugs to work they look for their target (cells/tissues) and to do so they interact with Receptors - proteins located inside or on the cells surface. 


Agonism - agonist drug molecules mimic normal physiological processes in the body -> binds to a receptor and activates -> generates response -> 


Antagonist Drug Molecules - inhibit/black an agonist from activating a receptor (can prevent opioid overdose. 


Neurotransmitters - brain chemicals that send messages to the body by binding with specific receptors 

  • Agonist drugs often mimic neurotransmitters / antagonist drugs inhibit them


Therapeutic Index (TI) - indicates the range of doses at which a medication is both effective and safe.

Narrow Therapeutic Index (NTI) -  have a small window between their effective doses and those at which produce acceptable adverse effects 

  • FDA recommends tight monitoring 

  • It’s monitored by trough and peak drug levels in the blood (Trough/Lowest and Peak/Highest) 

  • Trough is drawn before the administration of the next dose 

  • Peak is collected several hours after the drug administration depending on the drug. 


Drug Interactions - involve combinations of a medication with other substances that alter the effects on the body 

  • Drug-drug interactions, drug-disease interactions, drug-nutrient interactions, drug-herbal interactions, drug-alcohol interactions, and drug-laboratory interactions. 


Drug-Drug Interactions occur when two or more drugs react with each other.

  • 4 types - addition, antagonism, potentiation, synergism 


  1. Addition - combined effect of two drugs (sum of the effects of each drug taken alone) 

  •  One drug can add to the effects / side effects of another drug. 

  1. Antagonism  - the action of one drug antagonizes (blocks/works against) the action of another drug


  1. Potentiation - one drug enhances or prolongs the effect of another drug. 


  1. Synergism - the combined effect of the drugs is greater than the sum of the effects of the two drugs. (2+2=5)
     

Drug-Disease interactions - occur when adrug that is intended for therapeutic use causes certain harmful effects because of a disease or pre-existing condition that the patient has.  

  • Certain diseases or conditions may alter the absorption of elimination of some medications.


Drug-nutrient interactions - occur when certain foods or beverages increase/decrease the effects of drugs in the body. 


Drug-Alcohol interactions - occur for two main reasons - alcohol can have chemical reactions with the drug molecule itself and/or alcohol can have addictive harmful side effects with some drugs that are central nervous system depressants. 


Drug-Laboratory interactions - can interfere with laboratory testing and cause incorrect results 

  • Leads to wrong diagnoses, unnecessary testing, missed results. 


Indication - a reason to use a certain treatment. 


Contraindication - a reason not to use a certain treatment due to the harm that could cause the patient.