Essential Pharmacology: Mechanisms and Drug Classes
Oral Hypoglycemic Agents (OHAs)
Oral Hypoglycemic Agents (OHAs) are medications taken by mouth to help lower blood sugar levels in people with type 2 diabetes. They work by stimulating the pancreas to produce more insulin, improving the body’s sensitivity to insulin, or slowing down the absorption of glucose from the digestive tract.
Types of Oral Hypoglycemic Agents
Sulfonylureas
These stimulate the pancreas to release more insulin (e.g., glipizide, glyburide).
Meglitinides
Similar to sulfonylureas, these also stimulate insulin release (e.g., repaglinide, nateglinide).
Biguanides
Metformin, the most well-known biguanide, improves insulin sensitivity and reduces glucose production in the liver.
Thiazolidinediones
These increase insulin sensitivity, particularly in muscle and fat tissues (e.g., rosiglitazone, pioglitazone).
Drugs Used in Congestive Heart Failure (CHF)
Medications for CHF aim to lower blood pressure, reduce the heart’s workload, and manage fluid retention.
Key Drug Classes for CHF Treatment
ACE Inhibitors and ARBs
These medications lower blood pressure and reduce the heart’s workload by inhibiting the renin-angiotensin system. They also prevent heart muscle remodeling.
Examples: ACE Inhibitors: Captopril, Enalapril, Lisinopril. ARBs: Losartan, Valsartan.
Beta-blockers
These drugs block the effects of the sympathetic nervous system, which helps reduce heart rate and blood pressure. They also improve ejection fraction and reduce mortality.
Examples: Metoprolol, Bisoprolol, Carvedilol.
Diuretics
These medications help remove excess fluid and salt from the body, reducing fluid overload and improving breathing.
Examples: Furosemide, Thiazides.
Serotonin (5-HT) and Its Receptors
Serotonin, also known as 5-hydroxytryptamine (5-HT), exerts its effects through a family of receptors called 5-HT receptors. There are 14 distinct serotonin receptors, grouped into seven main classes (5-HT1 to 5-HT7).
Types of Serotonin Receptors
5-HT1 Receptors
This family includes subtypes 1A, 1B, 1D, 1E, and 1F. They are all G-protein-coupled receptors and are primarily inhibitory, often leading to decreased neuronal activity.
5-HT2 Receptors
This family includes subtypes 2A, 2B, and 2C, also G-protein-coupled receptors. They are involved in various functions, including arousal, attention, and anxiety.
5-HT3 Receptor
This is a ligand-gated ion channel, meaning it opens a pore in the cell membrane when serotonin binds, allowing ions to flow in and out. It is primarily excitatory and involved in nausea and vomiting.
5-HT4, 5-HT6, and 5-HT7 Receptors
These receptors are also G-protein-coupled and involved in various functions, including reward, memory, and cognition.
Functions of Serotonin Receptors
- Mood Regulation: Serotonin receptors play a role in mood regulation, with imbalances in the 5-HT1A and 5-HT2A receptors being linked to depression and anxiety.
- Sleep: Serotonin receptors, particularly 5-HT1A and 5-HT2A, are involved in regulating sleep-wake cycles.
- Digestion: Serotonin receptors, particularly 5-HT3 and 5-HT4, are involved in regulating gut motility and digestion.
Antifungal Drug Mechanisms and Side Effects
Pharmacology of Antifungal Drugs
Antifungal drugs work by disrupting fungal cell membranes, inhibiting vital enzyme activity, or interfering with fungal cell wall synthesis.
Side Effects of Amphotericin B
Amphotericin B is associated with several potential side effects, including:
- Blurred or double vision
- Convulsions (seizures)
- Numbness, tingling, pain, or weakness in hands or feet
- Shortness of breath, troubled breathing, wheezing, or tightness in chest
- Skin rash or itching
- Sore throat and fever
- Unusual bleeding or bruising
Anticancer Drugs (Chemotherapy)
Anticancer drugs, also known as chemotherapy drugs or antineoplastic agents, are medications used to treat cancer. They work by targeting and killing cancer cells, or by interfering with their growth and spread.
Major Classes of Anticancer Agents
Alkylating Agents
These drugs damage the DNA of cancer cells, preventing them from dividing and growing. Examples: cyclophosphamide and temozolomide.
Cytotoxic Antibiotics
This class of drugs interferes with DNA replication and function in cancer cells. Examples: doxorubicin and bleomycin.
Antimetabolites
These drugs interfere with the synthesis of essential molecules needed for cell growth, like DNA and RNA. Examples: methotrexate and 5-fluorouracil.
Pharmacological Treatment of Peptic Ulcers
Peptic ulcer drugs primarily focus on reducing stomach acid and protecting the stomach lining. Common types of medications include Proton Pump Inhibitors (PPIs), H2 Receptor Blockers, and Cytoprotective Agents.
Key Medication Types
Proton Pump Inhibitors (PPIs)
PPIs are the most effective at reducing stomach acid production. They work by blocking the enzyme that produces acid in the stomach.
Examples: omeprazole (Prilosec), lansoprazole (Prevacid), and pantoprazole (Protonix).
H2 Receptor Blockers
These drugs reduce acid production by blocking histamine receptors in the stomach.
Examples: famotidine (Pepcid), ranitidine (Zantac), and cimetidine (Tagamet).
Cytoprotective Agents
These medications help protect the stomach lining and promote healing. Misoprostol, a prostaglandin E1 analog, is sometimes used to prevent ulcers caused by NSAIDs.
Anticoagulant Drugs (Blood Thinners)
Anticoagulant drugs, also known as blood thinners, are medications that help prevent blood clots from forming or growing.
Types of Anticoagulants
Heparin
A fast-acting injectable anticoagulant that enhances the action of antithrombin III, a natural anticoagulant protein.
Warfarin
An oral anticoagulant that interferes with the production of vitamin K-dependent clotting factors in the liver.
Direct Oral Anticoagulants (DOACs)
A newer class of oral anticoagulants that directly inhibit specific clotting factors, such as factor Xa (rivaroxaban, apixaban, edoxaban) or thrombin (dabigatran).
Bronchodilator Drugs for Respiratory Health
Bronchodilators are medications that widen airways in the lungs, making it easier to breathe.
Types of Bronchodilators
Beta-2 Agonists
These medications relax the muscles around the airways, causing them to widen. They are often used as rescue inhalers to quickly relieve symptoms during an asthma attack.
Example: albuterol (ProAir, Ventolin).
Anticholinergics
These drugs also relax airway muscles by blocking the action of a specific chemical messenger in the body.
Examples: ipratropium (Atrovent) and tiotropium (Spiriva).
Methylxanthines
Theophylline (Theodur) is a less common type of bronchodilator that also helps relax airway muscles.