Drug Classes & Schedule Drugs Powerpoint

Classification of Drugs

Drugs are systematically organized to help healthcare providers manage medications efficiently. These organizations are primarily divided into therapeutic and pharmacologic categories, each serving a distinct purpose in clinical practice.

Therapeutic vs. Pharmacologic Classification

• Therapeutic Classification:

  • Focuses on the clinical usefulness of a drug in treating a particular disease or condition. It essentially answers the question: "What condition is being treated by this drug?"

  • Examples include anti-infectives, antidepressants, and anticonvulsants.

• Pharmacologic Classification:

  • Focuses on the drug's mechanism of action, or how a drug produces its physiological effect at the molecular, tissue, or body-system level. It answers the question: "How does this drug work within the body?"

  • This classification is often more specific than therapeutic classification and requires an understanding of biochemistry and physiology.

Organizing Drugs by Therapeutic Usefulness

• Cardiac Care: Many drugs are categorized by their specific effect on the cardiovascular system:

  • Anticoagulant: Influences blood clotting by interfering with the coagulation cascade to prevent thrombus formation.

  • Antihyperlipidemic: Lowers blood cholesterol levels to prevent atherosclerosis and heart disease.

  • Antihypertensive: Specifically targets the reduction of elevated blood pressure.

  • Antidysrhythmic: Used to restore a normal heart rhythm during episodes of arrhythmia.

  • Antianginal: Reduces the myocardial oxygen demand or increases supply to treat chest pain related to ischemia.

Organizing Drugs by Physiological Action (Pharmacologic Focus)

Pharmacologic classifications often provide a deeper understanding of the drug's interaction with receptors or enzymes:

• Diuretic: Increases the excretion of water and electrolytes by the kidneys, thereby lowering plasma volume and blood pressure.

• Calcium Channel Blocker: Inhibits the entry of calcium ions into heart and blood vessel cells, leading to vasodilation and decreased heart rate.

• ACE Inhibitor: Blocks the Angiotensin-Converting Enzyme, preventing the formation of Angiotensin II, a potent vasoconstrictor.

• Adrenergic Blocker: Inhibits the sympathetic nervous system's "fight or flight" response by blocking beta or alpha receptors.

• Vasodilator: Relaxes the smooth muscles in blood vessel walls, causing them to widen and lower peripheral resistance.

Drug Nomenclature and Naming Conventions

Drugs are identified by several names throughout their development and clinical use:

• Chemical Name: A strict nomenclature assigned by the International Union of Pure and Applied Chemistry (IUPAC) describing the exact molecular structure. While precise, they are rarely used in clinical settings due to their complexity.

• Generic Name: The official name assigned by the U.S. Adopted Name Council. These are written in lowercase (e.g., ibuprofen) and are universally recognized. Healthcare providers prefer generic names to avoid confusion between different brands.

• Trade Name (Brand Name): The proprietary name selected by the pharmaceutical company for marketing. These are capitalized (e.g., Advil) and protected by patent laws for $17$ years after the New Drug Application (NDA) is submitted to the FDA.

• Combination Drugs: Medications containing more than one active generic ingredient. These can be difficult to manage because the trade name may not clearly indicate all active components.

Comparison of Generic vs. Trade Name Drugs

• Bioavailability: This is the rate and extent to which the active ingredient is absorbed from a drug product and becomes available at the site of drug action. While generic and trade drugs must have the same active ingredients, inert fillers or tablet compression may affect bioavailability.

• Price and Access: Generic drugs are significantly more affordable as they do not require the initial research and development costs incurred by the original manufacturer.

• Negative Formulary: Certain states maintain a list of trade-name drugs that cannot be substituted with generic versions by a pharmacist due to narrow therapeutic indexes or critical bioavailability concerns.

Scheduled Drugs and the Controlled Substances Act

Under the Controlled Substances Act of $1970$, drugs with a high potential for addiction or abuse are placed into one of five schedules:

• Schedule I: No currently accepted medical use in the U.S. and a high potential for abuse (e.g., Heroin, LSD).

• Schedule II: High potential for abuse which may lead to severe psychological or physical dependence. Requires a written prescription with no refills allowed (e.g., Morphine, Oxycodone, Methamphetamine).

• Schedule III: Less potential for abuse than I or II but may lead to moderate physical or high psychological dependence (e.g., Anabolic steroids, Codeine with Tylenol).

• Schedule IV: Low potential for abuse relative to Schedule III (e.g., Diazepam, Alprazolam).

• Schedule V: Lowest potential for abuse, often used for antitussive or antidiarrheal purposes (e.g., Cough syrups with small amounts of codeine).

Pregnancy Safety Categories

To guide clinicians, the FDA established categories to classify the risks of drugs to a developing fetus:

• Teratogen: A substance that causes birth defects or malformations in an embryo or fetus.

• Category A: Controlled studies in women fail to demonstrate a risk to the fetus in the first trimester, and the possibility of fetal harm appears remote.

• Category B: Animal reproduction studies have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women.

• Category C: Animal studies show an adverse effect on the fetus, and there are no adequate studies in humans, but potential benefits may warrant use in pregnant women despite potential risks.

• Category D: There is positive evidence of human fetal risk based on adverse reaction data, but potential benefits may warrant use in pregnant women in life-threatening situations.

• Category X: Studies in animals or humans have demonstrated fetal abnormalities. The risk of using the drug in pregnant women clearly outweighs any possible benefit.