An Introduction to Pharmacology, 6th edition: Hitner and Nagle
Major areas of pharmacology
• Pharmacodynamics: Study of the action of drugs on living tissue
• Pharmacokinetics: Study of the processes of drug absorption, distribution, metabolism, and exertion.
• Pharmacotherapeutics: Study of the use of drugs in treating disease.
• Pharmacy: Science of preparing and dispensing medicines.
• Posology: Study of the amount of drug that is required to produce therapeutic effect.
• Toxicology: Study of the harmful effects of drugs on living tissue.
Schedule I: Drugs with high abuse potential and no accepted medical use (these drugs are not to be prescribed).
Heroin
Hallucinogens
Marijuana
Schedule II: Drugs with high abuse potential and accepted medical use (no refills without a new written prescription from the physician).
Narcotics (morphine and pure codeine)
Cocaine
Amphetamines
Short-acting barbiturates (Amobarbital, Secobarbital)
Nabilone
Schedule III: Drugs with moderate abuse potential and accepted medical use (prescription required, may be refilled five times in 6 months when authorized by the physician).
Moderate – and intermediate-acting barbiturates.
Dronabinol
Anabolic steroids
Preparations containing codeine plus another drug
Schedule IV: Drugs with low abuse potential and accepted medical use (prescription required, may be refilled five times in 6 months with authorized by the physician).
Phenobarbital
Chloral hydrate
Zolpidem (Ambien)
Antianxiety drugs (Librium, Valium)
Schedule V: Drugs with limited abuse potential and accepted medical use (drugs can be sold only by a registered pharmacist; buyer must be 18 years old and show identification. Some states require a prescription for schedule V drugs).
• Narcotic drugs used in limited quantities for antitussive (codeine) and antidiarrheal purposes (diphenoxylate, Lomotil)
Drug Forms
• Aqueous preparations: Syrups
• Alcoholic preparations: Elixirs, spirits, tinctures, and fluid extracts.
• Solid and semisolid preparations: Most common.
• Powders.
• Tablets.
• Troches and lozenges.
• Capsules.
• Delayed-Release.
• Enteric-Coated.
• Suppositories.
• Ointments.
• Transdermal Products.
• Parenteral injection.
Routes of Administration
• Oral
• Parenteral
Intramuscular injection.
Intravenous injection.
Drug Absorption:
*Refers to the entrance of a drug into the bloodstream.*
• Lipid solubility
• Drug ionization
• Drug formulation
Drug Distribution:
• Plasma protein binding
• Blood flow
• Blood-brain barrier
Drug Metabolism:
*Liver main organ involved in drug metabolism.*
• Drug microsomal metabolizing system (DMMS): System takes lipid-soluble drugs and chemically alters them so they become water-soluble compounds.
Water soluble compounds are excreted by the kidneys
Lipid soluble compounds are repeatedly reabsorbed into the blood.
• Enzyme induction
• Enzyme inhibition
Drug Excretion:
• Renal excretion
• GI excretion
• Respiratory excretion
• Miscellaneous
Half-life:
• The time required for the blood or plasma concentration of the drug to fall to half of its original level.
Blood Drug Levels:
• Loading dose
• Maintenance dose
Bioavailability:
*The percentage of the dose of a drug that is actually absorbed into the bloodstream.*
Factors of Individual Variation:
• Age
• Weight
• Sex and percent body fat
• Genetic variation
• Emotional state
• Placebo effect
• Presence of disease
• Patient compliance
Pharmacokinetic Considerations of Pediatrics:
• Fetal period during pregnancy
• Drug exposure during infant nursing
• Pediatric considerations
• Drug administration and absorption
• Drug distribution
• Drug Metabolism and excretion
• Dosage adjustment
Description of FDA Pregnancy Categories:
• Pregnancy category A: Drug studies in pregnant women have not yet demonstrated risk to the fetus.
• Pregnancy category B: Drug studies have not yet been performed in pregnant women; animal studies have not demonstrated fetal risk.
• Pregnancy category C: Drug studies have not been performed in pregnant women or in animals, or animal studies have revealed some teratogenic potential but the risk to the fetus is unknown.
• Pregnancy category D: Drug studies have revealed adverse risk to the fetus. The benefit-to-risk ratio of the drug must be established before use during pregnancy.
• Pregnancy category X: Drug studies have revealed teratogenic effects in women and/or animals. Fetal risk clearly outweighs benefit. Drug is contraindicated in pregnancy.
• Pregnancy category NR: Drug has not yet been rated by FDA.
Examples of Drugs with Demonstrated Teratogenic Risk in Humans:
• Androgens (male hormones): Masculinization of female fetus.
• Carbamazepine: Craniofacial and fingernail deformities.
• Diethylstilbestrol: Vaginal tumors and genital malformations in offspring.
• Estrogen (female hormone): Feminization of male fetus.
• Lithium: Cardiac defects.
• Phenytoin: Craniofacial and limb deformities, growth retardation.
• Retinoic acid: Craniofacial, cardiac, and central nervous system (CNS) defects.
Examples of Drugs that Cross into Breast Milk Following Maternal Use:
• Antibiotics: Ampicillin, erythromycin, penicillin, streptomycin, sulfa drugs, tetracyclines.
• Antiepileptic agents: Phenytoin, primidone.
• Antithyroid agents: Thiouracil.
• CNS stimulants: Nicotine.
• Laxatives: Cascara, danthron.
• Narcotic analgesics: Codeine, heroin, methadone, morphine.
• Nonnarcotic antiinflammatory agents: Phenylbutazone.
• Sedative-hypnotic agents: Barbiturates, chloral hydrate.
• Tranquilizers (antipsychotic agents): Chlorpromazine, lithium.
Drug Interactions:
*The effects that occur when the actions of one drug are affected by another drug.*
Terminology Associated with Chronic Drug Use and Abuse:
• Tolerance: Decreased drug effect that occurs after repeated administration.
• Drug dependence: Condition wherein reliance on the administration of a particular drug becomes extremely important to the well-being of an individual.
Drug abuse: When the drug is repeatedly used for nonmedical purposes.
Drug addiction: When drug dependence is severe and compulsive drug behavior dominates all other activities.