Absorption

• Process where a drug is taken up from the site of administration and is transported to the blood stream
  • Occurs:
  • Orally
  • Topically
  • Rectally
  • By inhalation
  • Parenteral
    
  • Examples:  ASA goes to stomach - absorbed in stomach; Enteric Coated ASA goes to intestine;  SQ Insulin absorbed under skin; IV goes directly into blood stream.

Distribution

• Process where a drug, once in the bloodstream, is delivered to specific organs and tissues in the body to exert its pharmacological effects
  • Example:  Aspirin goes to the stomach, then to the blood, then to the organ needing relief.  Headache

Metabolism

• Disappearance of a drug, when it changes chemically into another compound
• Takes place in many body organs - Primarily in the liver
• Usually enhances excretion and inactivation of a drug

Excretion

• Process by which the drug is eliminated from the body - Primarily by the kidney
• Drugs can be excreted via the urine, feces, lungs, skin, etc.

Bioavailability

• Percentage or fraction of the administered dose of a drug that actually reaches systemic circulation. Factors affecting oral route of administration include age, body weight and time of administration.

Therapeutic Incompatibility

• When the effectiveness of two drugs is decreased when given together.
  • Example: Ampicillin and Gentamicin therapeutic   incompatibility.

Therapeutic Duplication

•  
  • Example:  Cephalexin and Cefaclor are both Cephalsporins.  This is an example of therapeutic duplication.
• When two drugs from the same class are given together.

Adverse Effects

• Effects other than the desired ones.

An Anaphylactic Reaction

•  
  • Example: If a patient has a severe adverse reaction after prior administration of Penicillin.
• A severe adverse reaction to the administration of a drug.  This can cause anaphylaxis or anaphylactic shock.

Side Effects

• Effects that are predictable and widely reported:
• Undesired pharmacological effects of a drug seen when therapeutic doses of the drug are used.
• Often unavoidable, part of the drug's action.
  • Example:  Nausea, drowsiness, upset stomach, addiction

Toxicities

• Effects that are harmful and destructive to the body
• Causes:
• Drug dosage exceeds recommended dosage
• Drug is used for longer periods of time than is recommended
• Drug is not properly monitored
  • Example:  Chemotherapy kills good cells

Cross Sensitivity

• Allergic to drugs that are chemically similar (Penicillin & Ceflasporin)

Drug Interactions - Tech Should Notify Pharmacist

• A change in the magnitude or duration of the pharmacological response of one drug because of the presence of another drug

Possible Detrimental Effects

• Increased risk of side effects
• Increased risk of toxicities
• Decreased pharmacological response desired

Possible Beneficial Effects:

• Additive Response:
  • Occurs when two or more drugs combined together yield a response when the drugs by themselves are not enough
    
• Synergistic Response:
  • Occurs when the effect of two or more drugs is greater than the sum of the drugs
  • Example:  Bactrim, Septra, Trimethoprim and Sulfamethoxazole

A Theoretical Ratio

• Weigh risks vs. benefits
• Must be done on an individual basis
  • Example: Asthma patient should not be on a B blocker, Inderal.

Contraindicated

• When a drug used for one indication cause an increase in severity of another indication.
  • Example:  Pseudoephedrine contraindicated in hypertension