Pharmacology and ToxicologyScience and Policies

Nursing and Chemical Policies

Barbara Sattler, RN, DrPH, FAANUniversity of Maryland School of Nursing

Pharmacology vs. Toxicology

Pharmacology is the scientific study of the origin, chemical nature, effects and use of drugs.

Toxicology is the science that investigates the adverse effects of chemicals on health.

Dose

Pharmacology

Dose refers to the amount of drug absorbed from an administration

Toxicology

Dose refers to the amount of chemical introduced into a biological system

Administration

Pharmacology

Administration of a drug can be one time, short or long-term.

ToxicologyExposure is the

actual contact that a person has with a chemical. It can also be one time, short or long-term.

Dose-Response Curve

Pharmacology

Graphically represents the relationship between doses of a drug and the response elicited.

ToxicologyDescribes the

relationship of the body’s response to different amounts of an agent such as a drug or toxin.

Distribution, Metabolism, & Excretion

Pharmacology and Toxicology (ADME) Absorption is the amount of a substance that enters

the body Distribution: Organs/Tissues/Cells that are reached Metabolism: Chemical Transformation

/metabolites Excretion: Elimination/Persistence

Routes of Administration or Exposure

PharmacologyRoutes of

Administration: oral, IM, IV, inhalation, dermal, ocular, etc.

Toxicology

Routes of Entry: ingestion, inhalation, dermal absorption, ocular, etc

Pharmacology vs. Toxicology

In pharmacology there are therapeutic responses to drugs (desirable) and side effects (undesirable).

In toxicology only the negative health effects are of concern.

Potency vs. Toxicity

Pharmacology

Potency refers to the relative amount of a drug required to produce the desired response.

ToxicologyThe toxicity of a

chemical refers to the relative amount it takes to elicit a toxic effect compared with other chemicals.

Definition of Toxicity

Toxicity refers to the ability of a chemical to damage an organ system, to disrupt a biochemical process, or to disturb an enzyme system.

Three Types of Effects

Additive: the sum = the whole

Antagonistic: one reduces the effect of the other

Synergistic: one enhances the other’s effect

Cummulative exposures occur when multiple sources of one or more toxic chemical exist.

For example, in a single day, we can be exposed to pesticides in our homes, workplaces, and outdoors, as well as from the food we eat.

Mixturesand Multiple Cummulative

Exposures

Little is known about the toxic effects of multiple hazardous chemicals.

Biological Monitoring

Pharmacology

Bio-monitoring is done for some drugs: For example:

Clotting time is monitored for patients on coumadin.

Actual drug levels are measured for some drugs.

Toxicology

Bio-monitoring is done for some toxic exposures such as blood lead levels or metabolites of chemicals (biomarkers).

Index vs. Threshold

Pharmacology

Therapeutic Index is the relationship between a drug’s therapeutic effect and its adverse effects.

Toxicology

Threshold levels refers to the amount of a substance necessary to cause a response in the body.

Pharmacology/Toxicology

The effects of drugs and hazardous chemicals can be immediate (acute), long-term (chronic), or can present after a latency period.

Drugs are taken voluntarily and often under the supervision of a licensed health care provider.

Hazardous chemical exposures are most often involuntary.

Host Factors

Host factors must be considered for therapeutic drugs or hazardous chemicals. Factors such as age, genetics, weight, drugs that a person may be taking, pregnancy status, and others may impact the therapeutic or toxic effect of a drug or chemical.

Children's Special Vulnerabilities

Children… Are still developing and may have immature (more

sensitive) biological systems. Eat, breathe, and drink more per body weight than adults Eat a smaller range of foods (greater dairy and fruit/fruit

juices) Behave in ways that may place them at greater risk for

exposure Hand-to-mouth exploration Playing on the floor/ground

Regulatory Processes:Pre-market testing

The regulatory process by which a drug comes to the market includes several stages of testing, including both animal and human testing.

There is no requirement for pre-market testing of chemical products that are not foods, cosmetics, or pesticides. No original testing is required.

Toxicology Resources

Drugs Grateful Med (PubMed) OSHA:

http://www.osha.gov/dts/osta/otm/otm_vi/otm_vi_2.html

NIOSH: http://www.cdc.gov/niosh/docs/2004-165/

PDR Poison Control Centers

Hazardous Chemicals NLM Toxnet:

http://toxnet.nlm.nih.gov/ ATSDR Toxfaqs:

http://www.atsdr.cdc.gov/toxfaq.html

TRI Data: www.scorecard.org

HCWH: www.noharm.org OSHA: http://www.osha.gov/dts/osta/otm/otm_vi/otm_vi_2.html

New Evidence of Exposures

CDC “Body Burden” studies (NHANES) The “Egg” Study EWG “Cord Study”

Nursing Survey of workplace chemical exposures

If chemicals act like drugs, including causing physiologic changes (even at very low levels), shouldn’t they be regulated like drugs?

How can we exert our leadership in this emerging arena

?