Drug Interactions and Side Effects in Pharmacology

Weight Gain and Side Effects

• Common side effects include weight gain, gastrointestinal upsets, allergic skin rashes, and bone marrow damage.
• Gastrointestinal upset symptoms: anorexia, nausea, vomiting, diarrhea, and abdominal discomfort.
• Lactic acidosis is a rare but serious side effect associated with metformin use.

Drug Interactions

• Agents enhancing hypoglycemic effects:
  • NSAIDs
  • Coumarins
  • Alcohol
  • Sulfonamides
  • Primethoprimin
  • Chloramphenicol
  • Imidazole
  • Antifungal drugs

Sulfonylureas

• First generation includes:
  • Tolbutamide
  • Chlorpropamide
  • Tolazamide
• Second generation (fewer side effects and interactions):
  • Glyburide
  • Glipizide
  • Glimepiride

Biguanides

• Primarily represented by metformin and phenformin.
• Phenformin is discontinued due to lactic acidosis risk.
• Metformin half-life: 1.5-3 hours; not bound to plasma proteins and excreted by the kidneys.

Mechanisms of Action

• Metformin:
  • Stimulates glycolysis, increasing glucose removal from blood.
  • Reduces hepatic and renal gluconeogenesis.
  • Slows glucose absorption from the gastrointestinal tract.
  • Decreases plasma glucagon levels.
• Sulfonylureas:
  • Increase insulin release from the pancreas by binding to ATP-sensitive potassium channels, causing depolarization and calcium influx.

Clinical Use

• Both metformin and sulfonylureas are primarily used for type 2 diabetes management.
• Thiazolidinediones (PPARY agonists) facilitate adipocyte differentiation and enhance fatty acid and glucose uptake.

Side Effects Overview

• Sulfonylureas lead to hypoglycemia.
• Thiazolidinediones can cause weight gain, fluid retention, headache, fatigue, and gastrointestinal upset.

Dipeptidyl Peptidase-4 (DPP-4) Inhibitors

• Examples: Sitagliptin, Saxagliptin, Linagliptin.
• These drugs increase levels of natural GLP-1, reducing postprandial glucose excursions by enhancing insulin secretion and lowering glucagon levels.

Other Drug Classes

• Bile acid sequestrants like Colesevelam are designed for cholesterol-lowering but affect glucose regulation.
• GLP-1 receptor agonists increase insulin secretion while lowering glucagon levels, reducing appetite, and slowing gastric emptying.

Important Notes

• Metformin is contraindicated in individuals with renal or hepatic diseases, hypoxic pulmonary diseases, or heart failure.
• Sulfonylureas are generally contraindicated in pregnancy due to potential fetal hypoglycemia.

Explore the complexities of drug interactions, side effects, and the specific types of sulfonylureas in this quiz. Learn about the various agents that may augment hypoglycemic effects and the associated risks, including gastrointestinal issues and allergic reactions. Perfect for students studying pharmacology or medicine.