Clinical Pharmacology and Therapeutics: Foundations and Core Principles
Introduction to Clinical Pharmacology and Therapeutics
Course Orientation: While the subject is called pharmacology, the specific focus is on therapeutics or clinical pharmacology.
Application-Driven Study: The purpose of the study is to apply pharmacological principles to therapy. While many drugs exist in various systems, not all are utilized in a clinical setting to treat, investigate, or prevent conditions.
Bench Side to Bedside: This phrase represents the transition of drug information from the laboratory setting—where tests are conducted on animal models or in vitro (in glass tubes)—to the clinical environment for patient management and therapeutic intervention.
Clinical vs. Experimental Pharmacology: The course emphasizes clinical pharmacology rather than experimental pharmacology. This means focusing on how pharmacological principles apply to clinicians and the specific patients they manage.
Broad Branches of Pharmacology
Pharmacokinetics: Defined as the effect of the body on the drug.
Etymology: Derived from pharmako (drug) and kinetic (motion, as in kinetic energy).
Mechanism: It describes how the body affects or impedes a drug as it transits from the site of administration to its target site.
Body Characteristic Example: Two patients with the same condition (malaria) are given an anti-malarial drug that requires a lipid (fat) substrate to dissolve.
Patient A has significant fat deposition.
Patient B has minimal fat deposition.
The drug works better in Patient A because the fat allows for complete dissolution. The drug's lack of efficacy in Patient B is not due to the drug's properties but because of the patient's physical characteristics affecting the drug. This is a pharmacokinetic phenomenon.
Pharmacodynamics: Defined as the effect of the drug on the body.
Etymology: Derived from pharmako (drug) and dynamics (change).
Mechanism: This involves the changes the drug induces in the body, which is the primary goal of taking medication.
Toxicology: A dedicated field of interest regarding toxins and poisons.
Clinical Relevance: Clinicians must be able to identify potential poisons and their various sources to better treat patients who have ingested toxins.
Drug Information and History
Etymology of Pharmacology: A "Twitter word" (portmanteau) where pharmakon refers to the drug, active ingredient, or active principle, and logos refers to the science or study of it.
The Importance of Drug History: Understanding the history of a drug allows clinicians to apply it effectively in practice, particularly regarding drug repurposing.
Drug Repurposing Examples:
Misoprostol: Historically developed as a synthetic prostaglandin analog for the treatment of peptic ulcers (gastric protection). It works by binding to prostaglandin receptors on parietal cells to reduce gastric acid secretion. However, it was discovered to also bind to uterine smooth muscle cells, causing contractions. Now, it is used in labor wards and after CA to help the uterus contract and expel contents.
Nifedipine: Traditionally known as an anti-hypertensive medication but is repurposed in obstetric wards to abort fast contractions.
Drug Sources and Composition: Knowledge of whether a drug is natural or synthetic is vital for safety. For instance, knowing if a drug is sulfur-based is critical for patients with specific allergies or conditions such as a deficiency in dyskinesia that could lead to life-threatening reactions if exposed to sulfur.
Standard Pharmaceutical Profile: For every drug, clinicians should know its history, source, properties, compounding (ingredients), physiological effects, pharmacokinetics, pharmacodynamics, therapeutic effects, mechanism of action, indications, side effects, precautions, adverse drug reactions, interactions, and contraindications.
Defining Drugs and Medicines
Definition of a Drug: Any substance capable of causing a change in biological function or an alteration of state through a chemical reaction.
Biological Change Examples:
Food: If a person is hypoglycemic (low blood sugar) due to starvation and eats food, their state changes from hypoglycemic to normal glycemic. This involves chemical interactions; therefore, under a broad scientific definition, food could be considered a drug.
Alcohol: Classified as a drug because it causes a physical change and an alteration in body state and function.
Nicotine and Marijuana: Classified as drugs because they induce biological changes.
Definition of Medicine: Drugs that are specifically used for therapeutic purposes, such as diagnosing, treating, or preventing diseases (prophylaxis).
The Conceptual Relationship: "All medicines are drugs, but not all drugs are medicines." Medicines are a specific subset of drugs intended for healing and health management.
Dosage and Toxicity
The Dose-Poison Relationship: Paracelsus famously stated, "It is the dose that makes the poison."
Regulated Dosing: The difference between a therapeutic medicine and a poison is often just the dose.
Example: Paracetamol at is therapeutic. If taken in excess of regulated amounts, it becomes a poison.
Therapeutic Index: Drugs with a "narrow therapeutic index" are particularly dangerous. An alteration as small as or even in the dose can predispose a patient to poisoning.
Phases of Drug Action
Oral Formulations: Approximately of drugs administered are of oral formulation (enteral administration).
Clinical Preference: Hospitals prefer oral routes over parenteral (injections) whenever the patient is conscious and capable of taking medication by mouth.
Formulation Types: These include tablets, capsules, and others.
Questions & Discussion
Recording Requests: A student named Zita requested the class be recorded. The instructor noted that no one in the session was currently the host, making recording from their end difficult. The instructor encouraged students to listen closely as they had limited time (only one month) for the course.
Technical Issues and Disruptions: The instructor addressed issues with students accidentally unmuting themselves (specifically mentioning user Obisa). He requested a student named Humphrey to contact IT (Donnie) to grant host or co-host privileges to manage the audio and muting of the class.
Student Contributions on Drug Use:
Justice contributed that Misoprostol is used for uterine contractions and CA management but correctly noted its original purpose was for ulcer treatment.
Kobi asked for clarification regarding the definitions of drugs versus medicines after his connection was interrupted. The instructor clarified that drugs cause biological changes, while medicines are drugs used specifically for therapy.
Administrative Guidance: The instructor asked students to ensure their actual names are displayed on their accounts so he can accurately identify and address them during contributions.