Chapter 10- Pharmacology
Pharmacokinetics- how the drug moves inside the body
Pharmacodynamics- how drug affects the body
Toxicology- study of the body’s response to poisons
Antibiotics- drugs that affect bacteria only
Drugs can be identified by therapeutic action (e.g. antimicrobials, analgesics)
Drugs have three names:
 Chemical- accurate chemical description
 Brand name- proprietary or trade name (e.g. Tylenol)
 Generic- non-proprietary, assigned by the US Adopted Names Council (e.g. acetaminophen)
Pharmacokinetics involves:
 Drug Administration:
 Enteral (via GIT): orally, rectally, sublingually
 *Parenteral (via systems other than the digestive symptoms)- injection, inhalation
o *Local (topical)- on skin & mucous membrane, sublingual
Inhalation
o Systemic: intravenous ?
o Most dangerous is intravenous (most instant absorption)
o Intradermal – inside skin
o *Intraarticular- inside joint
o *Intrathecal- in subarachnoid space of spinal cord
o Intracardiac – inside the heart muscle
 Drug Absorption
 Drug is taken from site of administration into blood
 Sites of action
o Extracellular (e.g. heparin, affecting proteins outside cells)
o Cellular (e.g. acetylcholine  muscle cell contraction)
o Intracellular (e.g. sulfa drugs, inhibit intracellular components needed for bacterial growth)
 Rate of absorption is influenced by (direct relationship)
o Surface area
o Rate of dissolution
o Lipid solubility
o Blood flow
 Drug Distribution: transfer of drugs across biological membranes into body compartments
 Drug Biotransformation (Metabolism)
 Liver- main organ
 Other organs involved are: lung, kidney, and adrenal gland
 Liver has cytochrome P450 that are enzymes that break down drugs
 Drug Clearance (Elimination)
 Primary via kidneys
 Some drugs are excreted via bile, breast milk, expired air, sweat, saliva & tears
Dose Effect:
 Dose of a drug is the amount given at a single time
 Dosage is the total amount given over a period of time
Therapeutic Index: “Margin of Safety”
 Ratio between the drug dose causing undesirable effects & the dose causing desired therapeutic response
 TI = LD50/ED50
 High therapeutic index = drug is relatively safe
 Low therapeutic index = drug is relatively unsafe
Toxic Effects:
 *Typically occurs due to depletion of enzymes necessary for detoxification of a drug
 *Affected by many factors in addition to overdose
 Liver and kidney disease
 Starvation
 Age
 Genetics
 Gender
Toxicity
 Acute- effect occurs within minutes or hours after first exposure
 Subacute- occurs after days of exposure
 Chronic- occurs over months to years during which time the rate of exposure exceeds the rate of
elimination
Public Safety
 FDA (Food & Drug Administration)
 DEA (Drug Enforcement Administration)
 Controlled substances- 5 schedules established by DEA
o 1 – highest risk of abuse
o 5- lowest risk of abuse
Chapter 11- Antimicrobial Drugs
Mechanisms of Antimicrobial Action
 Microbicidal- kills microbes & can kill normal flora
 Microbiostatic- inhibits growth
Modes of Action
 Inhibition of cell wall synthesis (e.g. penicillin & cephalosporins)
 Inhibition of Protein Synthesis
o Eukaryotic ribosomes not affected (e.g. macrolides and tetracyclines)
 Ribosomes in eukaryotic cells are larger
 Bacteria is looking for smaller ribosomes
 Inhibition of Nucleic Acid Synthesis (e.g. Quinolones)
 Disruption of plasma membrane
o Can affect prokaryotic and eukaryotic cells (e.g. polymyxin B and some antifungals)
 Inhibition of Metabolic pathways (e.g. Sulfa drugs & Trimethoprim)
Spectrum of Action
 Broad spectrum- effective against large variety of microorganisms
 Medium spectrum- effective against some gram-positive and gram-negative bacteria, not all
 Narrow spectrum- effective against relatively small variety of organisms, avoids damage to normal flora
Selective Toxicity


Kills only pathogens
NO significant damage to host (human body)
Determination of Efficacy
 Kirby-Bauer or disk diffusion method
 Dilution or minimal
 Serum Killing Power- uses patients blood while on medication, test it with bacteria
Multiple Resistance to Antimicrobial Drugs
 Primarily develop in healthcare facilities
 “Superbugs”
 MRSA
 VRE- Vancomycin Resistant Enterococcus
Mechanism of Resistance
 Change in membrane permeability
 Increased drug elimination
 Change in target (receptor)
 Change in a metabolic pathway
 Development of defensive enzymes
Preventing Drug Resistance
 Hand washing
 Eliminate unwarranted use of antibiotics
 Target a narrow range of microbes
 Use drug combinations (synergism)  increases risk of allergies
 Isolation of facilities with ongoing infections
 Antibiotics must be taken as prescribed
 Leftover medications should be discarded
 Do not take anyone else’s prescription
Antibacterial Agents
 Natural
o Produced by a microorganism
o E.g. pencillin (produced by Penicillium chrysogenum (fungus)
 Semisynthetic
o Chemically modified natural antibiotic (ampicillin)
 Synthetic
o Produced in lab
o E.g. Sulfa, trimethoprim, quinolones
Synthetic Antiviral Agents
 Acyclovir (Zovirax)
o Interfere with viral replication
o Promotes healing
o Reduces pain
 Amantadine- mainly used against flu
 Azidothymidine (AZT)
 Interferons
o Produced by viral infected cells
o Produced antiviral agent in neighboring normal cells
Metronidazole- antiprotozoal and antifungal
 Antibacterial- anaerobic (can live with oxygen)
Anthelminthic Agents
 Niclosamide
 Mebendazole
 Piperazine
 *Ivermectin
Q1. B. Intravenous
Q2. D. Nonproprietary
Q3. B. Extracellular
Q4. B. Kidneys
Q5. C. No longer can multiply
Q6. C. Medium-spectrum
Q7. A. Polymerase Chain Reaction (PCR)
Q8. A. Change in ribosome composition
Q9. A. Amantadine
Chapter 12- Infection & Diseases
will not cover Chapter 13
Host-Microbe Relationship
 Under normal circumstances, fetus in utero is free of microbes
 During birth, a newborn is exposed to microbes, which will start to colonize the infant’s intestine
 Symbiosis- a close relationship between two different species of organisms in a community
o Mutualism- both members benefit from the interaction (e.g. E. coli in the human GI tract)
o Commensalism- one organism benefits and the other is neither harmed nor helped (living on
secretions and dead cells) (normal flora)
o Parasitism- one organism benefits, while the other is harmed (e.g. T.B., helminths, and protozoa)
o Amensalism- one organism can hamper or prevent the growth/survival of another, without being
affected by the other organism (e.g. penicillium)
Normal Flora (Microbiota)
 *Resident flora- normal flora throughout the life of a person (e.g. S. epidermidis & E. Coli)
 *Transient flora- remain for a few hours, days, or months before they vanish (e.g. Bacillus
Laterosporus (sometimes lives in intestine to limit growth of Candida)
 Normal flora are usually protective so, they do not cause diseases in their normal habitat in a health
person
 When balance is interrupted, normal flora can become opportunistic pathogens
Portal of Entry
 Exogenous (comes from outside)
 Endogenous (comes from inside)
 Majority of germs have their preferred portal of entry
 If pathogen enters the “wrong” portal, infection will not occur
 Some infectious agents enter via more than one portal (e.g. streptococcus and staphylococcus)
 Skin & mucous membranes

Placenta: some microbes across placenta causing spontaneous abortions, birth defects, or premature (e.g.
HIV, Rubivirus, Cytomegalovirus, Parvovirus B-19), Toxoplasma gondii
Virulence
 Virulence- the degree of pathogenicity or disease provoking power of a specific microbe
 Virulence factors
 *First step of infection
 *By pili & cell membrane proteins
Colonization of tissues…
Evasion of Host Defense
 *Avoid contact with phagocytes
 *Inhibition of phagocytic engulfment
 *Survival inside the phagocytes
 *Production of products that kill or damage phagocytes before or after ingestion
Toxins (*major virulence factor*)
 Toxigenesis- ability of organism to produce toxins
 Bacterial toxins can act on sites remote from the original site of infection
 *Endotoxin (inside)
o Present first in the cell wall, release only when cell wall opens
o Lipopolysaccharides
o Heat-stable (not affected by heat)
 *Exotoxin (outside
o Proteins
o Heat labile (damaged by heat)
Portal of exit
 Site of pathogen leaving infected person
 Often same as portal of entry
 Pathogen can also leave host by defecation, blood, nasal secretions, saliva, sputum, respiratory droplets,
tears, earwax
 Etiology of Infectious Disease- the study of the cause of disease