1. General Pharmacology
Pharmacokinetics
Pharmacokinetics involves the study of drug absorption, distribution, metabolism, and excretion (ADME). Understanding these processes is crucial for determining appropriate drug dosing.
Absorption
Absorption is the process by which a drug enters the bloodstream. Factors like route of administration, drug solubility, and pH can influence absorption.
Distribution
Distribution refers to how the drug is dispersed throughout the body. It depends on factors like blood flow, tissue permeability, and protein binding.
Metabolism
Metabolism is the chemical alteration of a drug in the body, primarily in the liver. Enzymes such as cytochrome P450 play a significant role in this process.
Excretion
Excretion is the removal of drugs from the body, mainly through the kidneys. Understanding renal function is essential in adjusting drug dosages.
Pharmacodynamics
Pharmacodynamics deals with the effects of drugs on the body and their mechanisms of action, including receptor binding, post-receptor effects, and chemical interactions.
Dose-Response Relationships
This concept explains the relationship between drug dose and the magnitude of the drug effect. It is crucial in determining the therapeutic window.
Drug-Receptor Interactions
Drugs typically act by binding to specific receptors in the body. Understanding the nature of these interactions helps in designing drugs with better efficacy and safety profiles.
2. Cardiovascular Pharmacology
Drugs Used in Hypertension
Hypertension is managed by various drug classes, including diuretics, ACE inhibitors, and calcium channel blockers. Each has a unique mechanism of action and side effect profile.
Classes of Antihypertensive Drugs
Common classes include diuretics (e.g., hydrochlorothiazide), ACE inhibitors (e.g., enalapril), calcium channel blockers (e.g., amlodipine), and beta-blockers (e.g., metoprolol).
Mechanisms of Action
Each class reduces blood pressure through different mechanisms, such as reducing blood volume (diuretics) or dilating blood vessels (ACE inhibitors and calcium channel blockers).
Clinical Case Example
A patient with resistant hypertension may require combination therapy, involving drugs from different classes to achieve optimal blood pressure control.
Table: Side Effects and Contraindications of Common Antihypertensive Drugs
| Drug Class | Common Side Effects | Contraindications |
|---|---|---|
| Diuretics | Hypokalemia, dehydration | Renal failure |
| ACE Inhibitors | Cough, hyperkalemia | Pregnancy, renal artery stenosis |
| Beta-blockers | Bradycardia, fatigue | Asthma, severe heart failure |
3. Central Nervous System Pharmacology
Antidepressants and Anxiolytics
These drugs are used to treat mood and anxiety disorders by modulating neurotransmitters such as serotonin, norepinephrine, and GABA.
Classes
Common classes include SSRIs (e.g., fluoxetine), SNRIs (e.g., venlafaxine), tricyclics (e.g., amitriptyline), and benzodiazepines (e.g., diazepam).
Mechanisms of Action
These drugs work by affecting neurotransmitter levels or receptor activity in the brain, thereby alleviating symptoms of depression and anxiety.
Side Effects
Side effects can include weight gain, sexual dysfunction, and withdrawal syndromes, which must be carefully managed.
Clinical Case Example
A patient with depression and a history of substance abuse may require careful selection of an antidepressant to avoid potential drug interactions and dependence.
Diagram: Serotonergic and Adrenergic Pathways in the CNS
4. Endocrine Pharmacology
Diabetes Management
Managing diabetes involves using various classes of drugs to control blood glucose levels, including insulin and oral hypoglycemic agents.
Insulin Therapy
Insulin therapy is critical in type 1 diabetes and often required in advanced type 2 diabetes. Different insulin types, such as rapid-acting and long-acting, are used to mimic natural insulin secretion.
Oral Hypoglycemics
Oral agents such as metformin and sulfonylureas are used primarily in type 2 diabetes. These drugs work by increasing insulin sensitivity or stimulating insulin secretion.
Clinical Case Example
A patient with newly diagnosed type 2 diabetes might start on metformin, with adjustments made based on glycemic control and tolerance.
Table: Insulin Types and Their Onset, Peak, and Duration
| Insulin Type | Onset (min) | Peak (hours) | Duration (hours) |
|---|---|---|---|
| Rapid-acting (e.g., Lispro) | 15 | 1-2 | 3-5 |
| Long-acting (e.g., Glargine) | 60 | None | 24 |
5. Special Considerations in Pharmacology
Pediatric Pharmacology
Pediatric patients require special dosing considerations due to differences in drug absorption, metabolism, and excretion compared to adults.
Dosing Guidelines
Dosing in children is often weight-based (mg/kg). Special care must be taken to avoid dosing errors in this population.
Clinical Case Example
A child with acute otitis media may require careful calculation of amoxicillin dose based on weight to ensure efficacy and minimize side effects.
Table: Drug Dosing Guidelines in Pediatric and Geriatric Patients
| Patient Group | Considerations | Dosing Guidelines |
|---|---|---|
| Pediatrics | Immature liver and renal function | Weight-based dosing |
| Geriatrics | Reduced renal function | Lower starting doses |
