Pharm Chapter 3 Notes

What is a drug?

Any chemical substance ingested or applied to the body to affect function

What are some sources of drugs?

• Plants

• Minerals

• Animals

• Synthetics tech

  • More common now

  • Probably the most actively pursued source of drugs by major companies

What is genetic engineering?

The alteration of genes in a lab setting.

Recombinant DNA technology

Allows for the production of biologically active substances that are in the body

Combines DNA of two or more different organisms

Can treat certain diseases; possibly useful in gene therapy and/or preventative medical therapy

What is a common characteristic of all drugs?

They affect body function: cellular changes (drug actions), followed by some physiological change (effects of drugs)

Describe the systemic effect of a drug.

Reaches widespread areas of the body

Describe the local effect of a drug

Limited to the area of the body where it is administered

Define pharmacokinetics

What happens to the drug as it moves (processes) throughout the body

List the four drug processes

• Absorption

• Distribution

• Metabolism

• Excretion

  Acronym: ADME

Define Absorption

Passage through membrane into bloodstream

Define Distribution

Movement from bloodstream to cells/tissue/fluids of body

Define Metabolism

Physical and chemical alterations that a substance undergoes in the body

Define Excretion

Elimination of waste products of drug metabolism from the body

What conditions may alter the processes of Absorption?

Mucosa of the stomach, mouth, small intestine, or rectum; blood vessels in the muscles or subcutaneous tissues; or dermal layers.

Incorrect administration may destroy the drug before it reaches the bloodstream or its site of action.

What conditions may alter the processes of Distribution?

• Circulatory system, through capillaries and across cell membranes

• Poor circulation (impaired flow of blood) may prevent the drug from reaching tissues where it is to have its desired effect.

What conditions may alter the processes of Metabolism?

• Liver, small intestine

• Hepatitis, cirrhosis of the liver, or a damaged liver may prevent adequate breakdown of the drug, thus causing a build-up or accumulation of unmetabolized drug.

What conditions may alter the processes of Excretion?

• Kidneys, sweat glands, lungs, or intestines

• Renal damage or kidney failure may prevent passage of drug waste products, thereby causing an accumulation of the drug in the body.

Define Absorption

Getting into bloodstream

Site of absorption varies due to what?

Physical properties of each drug:

• pH

• Lipid Solubility

• Water

• Food

How does pH affect absorption?

Drugs slightly acidic absorb well in stomach

If alkaline, not absorbed well in stomach; better in small intestine

How does lipid (fat) solubility affect absorption?

• Higher lipid content easier/faster absorption in stomach

• Lower lipid content absorbed better if not given through GI tract

How does food in the stomach affect absorption?

• Food in stomach slows absorption of drugs

• Faster absorption on empty stomach

Define Distribution

Moving from bloodstream into tissues and fluids

Specific properties of drugs vary, such as:

Blood-brain and placental barriers; Selective distribution

• Affinity or attraction of drug to specific cell or organs

• Rates of distribution can vary within the same drug classification

Define Metabolism

Physical and chemical alterations that a substance undergoes in the body, happens in the liver, due to the effects of hepatic disease some drugs bypass this process

Biotransformation (liver)

Drug is broken down and altered to more water-soluble byproducts (easier to excrete by kidneys)

Prodrugs

Inactive when administered and only become active when metabolized by the liver

What is excretion?

Eliminating waste products of drug metabolism

• Kidney function primarily. Some elimination through lungs, perspiration, feces, bile, or breast milk

• Cumulative effect important with kidney function

• Increased effect when repeated dosages accumulate

• Toxicity: exposure to poison or dangerous amount of drug

Define the therapeutic range

Desired effect; amount below level of toxic effect or causing serious side effects

What other variables affect drug action?

• Age: metabolism and excretion are slower in older adults; children have a lower threshold of response.

• Weight: generally, the bigger the person, the greater the dose.

• Male/Female: females may respond differently

• Body fat content, hormones

• Psychological state: positive feelings may result in more positive responses

• Placebo effect: Environment affects

Define drug interactions

Can be desirable or undesirable

Define synergism in the context of drug interactions

Drugs work together to produce a desired effect

Define potentiation in the context of drug interactions

One drug increases/prolongs effect of another

Define antagonism in the context of drug interactions

Drugs oppose each other to decrease/cancel effect

List other variables affecting drug action

• Dosage: Minimum/Maximum; Loading; Maintenance; Toxic; Lethal

• Therapeutic Range: Therapeutic range

Define pharmacogenomics

Examines how genes may explain a drug's effectiveness and toxicity

How are routes of administration selected?

Selected based on speed, cost, or safety

Name the enteral or GI tract routes

• Oral (PO)

• Nasogastric tube (NG)

• Rectal (R)

Name the parenteral routes

Injection Routes, standalone routes

What are the Enteral administrations?

• Oral, Rectal, Nasogastric tube

• Absorbed in stomach Intestines

Injection routes

• Intravenous (IV)

• Intramuscular (IM)

• Subcutaneous (subcu)

• Intradermal (ID)

• Intraspinal, intraventricular, and intracapsular

Standalone routes

• Sublingual (SL) or buccal – mucosa without swallowing Not Entrol

• Topical

• Dermal

• Transdermal

• Transvaginal

• Nasal

• Ophthalmic or Otic

• Inhalation

Define adverse drug reactions (ADRs)

Unintended side effects from medications

What is a teratogenic effect?

Maternal drug administration causes development of physical defects in a fetus.

Define idiosyncratic reaction

Unique, unusual, and unexpected response to a drug

Define paradoxical reaction

Opposite effect from that which is expected

Define tolerance

Decreased response to a drug that develops after repeated doses are given

Define dependence

Acquired need for a drug that may produce psychological or physical symptoms of withdrawal when discontinued

Define hypersensitivity

Immune response (allergy) to a drug may vary

Define anaphylactic reaction

Severe, possibly fatal, allergic (hypersensitivity) response