Therapeutic Drugs and Toxicology Part 1

Key Concepts in Pharmacology and Therapeutic Drug Monitoring

  • Consideration of # Glycoside Antibiotics

    • Mean Glycoside Antibiotics:

    • Defined as a drug with a narrow therapeutic range.

    • There is a fine line between therapeutic (effective) and toxic doses.

    • Requires careful management of drug levels to avoid toxicity.

    • Terms:

    • Therapeutic: Used for medicinal purposes.

    • Toxic: Can arise from illicit drugs or an excess of a therapeutic drug.

    • A therapeutic drug can become toxic if accumulation occurs in the body.

    • Body's Role:

    • Important to manage the drug's clearance from the body.

Uses for Therapeutic Drug Monitoring

  • Maximize Therapeutic Effect.

  • Minimize Toxicity.

  • Optimize Benefit to the Patient.

  • Check Patient Compliance:

  • Relevant for adults and children, especially in conditions like ADHD.

  • Individuals may misuse prescribed drugs for financial gain.

Pharmacokinetics Overview

  • Four Key Processes:

  • Absorption:

    • The process from administration until the drug enters blood circulation.

    • Most absorption for oral drugs occurs in the small intestine.

    • Drug is absorbed in the stomach or small intestine and passes directly to the liver via portal vein by passing rest of circulation

  • Distribution:

    • Movement of the drug from the intestines to tissues for action.

    • movement of drug from blood to tissue and vise versa

    • Only the free unbound drug is active

    • The drug that is bound to albumin is inactive

  • Metabolism:

    • Biotransformation of drugs to metabolites, which may be active or inactive.

    • Generally occurs in the liver.

  • Elimination:

    • Refers to how the drug exits the body, primarily through the kidneys.

    • Factors affecting it include age, health, gender, and concurrent medications.

Clinical Implications of Pharmacokinetics

  • Atypical Pharmacokinetics: Factors influencing drug metabolism include:

  • Age

  • Pregnancy

  • Disease

  • Pregnancy Effects:

  • Increased metabolism and excretion, resulting in decreased drug concentration.

Therapeutic Drug Monitoring Practices

  • Peak and Trough Levels:

  • Trough Level: The lowest concentration in the bloodstream before the next dose; collected within 30 minutes prior to administration.

  • Peak Level: The highest concentration; typically collected at different intervals depending on the route of administration (e.g., 30 minutes post-IV or 1 hour post-oral).

  • Monitoring Drugs like Gentamicin:

  • Importance due to nephrotoxic and ototoxic effects.

Measurement Methodologies for Therapeutic Drugs

  • Common methodologies:

  • Chromatography: Generally used in research.

  • Immunoassay: Most frequently used in the United States, especially for cancer.

  • ISE: Used for lithium monitoring.

Examination of Drug Classes and Effects

  • Amphetamines:

  • Stimulants including Methamphetamine and Ecstasy.

  • Anabolic Steroids:

  • Used to increase muscle mass; excess can lead to hormonal imbalances.

  • Cannabinoids:

  • Psychoactive substances derived from marijuana (e.g., THC).

  • Cocaine:

  • Functions as both a local anesthetic and a CNS stimulant.

  • Opiates:

  • Provided pain relief but can lead to addiction (e.g., Morphine, Heroin, Fentanyl).

  • Sedative and Hypnotics:

  • Classes of drugs originally prescribed for anxiety and sleep disorders; includes benzodiazepines.

Specimen Types for Drug Testing

  • Types:

  • Serum, Plasma, Urine.

  • Chain of Custody:

  • Essential in maintaining the integrity of specimens used for drug testing.

Considerations in Toxicology

  • Lead Poisoning Effects:

  • Causes cognitive decline, behavior problems in children, and competes with iron and hemoglobin.

  • Detection Mechanisms:

  • Specimen collection requirements vary; typically use EDTA tubes.

Vitamins and Their Importance

  • Vitamin A:

  • Crucial for dim light vision.

  • Vitamin C:

  • Ascorbic acid, essential for various physiological functions.

  • Vitamin D:

  • Important for bone health; often linked with calcium.

  • Vitamin E:

  • Powerful antioxidant.

  • Vitamin K:

  • Critical for blood coagulation.

Iron Metabolism and Deficiency Disorders

  • Iron Deficiency:

  • Characterized by decreased serum iron, increased total iron binding capacity (TIBC), decreased transferrin, and low ferritin levels.

  • Crucial Points:

  • Ferritin serves as an acute phase reactant; levels can rise during inflammation.

  • ## Conclusion and Future Steps

    • Review further aspects of Lesson 13 when next convened, maintaining an engagement with the material through revisiting concepts discussed above.