Buffers are integral to maintaining proper function and stability in both pharmaceuticals and biological systems.
Pharmaceutical Buffers
Purpose:
Stability: Many drugs are pH-sensitive; buffers maintain pH to prevent degradation.
Solubility: The solubility of active ingredients can depend on pH.
Efficacy and Safety: Proper pH ensures optimal drug action and minimizes irritation.
Applications:
Injectable Preparations: Must match physiological pH to avoid tissue damage.
Ophthalmic Solutions: Buffered to match the pH of tears (~7.4) for comfort.
Oral Medications: Buffers protect active ingredients from stomach acid or aid absorption.
Common Buffer Systems:
Citrate Buffers: Used for a pH range of 3.0–6.2.
Phosphate Buffers: Effective between pH 5.8–8.0.
Acetate Buffers: Used in the pH range of 3.6–5.6.
Biological Buffers
Role in Physiology:
Homeostasis: Buffers maintain constant pH in bodily fluids, crucial for life.
Enzyme Activity: Enzymes have optimal pH ranges; buffers ensure these conditions.
Metabolic Processes: pH affects metabolic pathways and energy production.
Major Biological Buffer Systems:
Bicarbonate Buffer System
Predominant in blood plasma.
Regulates pH through respiratory (CO₂ exhalation) and renal (bicarbonate excretion) mechanisms.
Phosphate Buffer System
Active in intracellular fluids and kidneys.
Important in urine pH regulation.
Protein Buffers:
Amino acids and proteins act as buffers due to their functional groups.
Hemoglobin in red blood cells buffers pH during oxygen and carbon dioxide transport.
Here's a small table summarizing body fluids, their pH values, and their buffer systems:
Body Fluid | pH Value | Body Fluid | pH Value | Buffer System |
Blood Plasma | 7.35 - 7.45 | Blood Plasma | 7.35 - 7.45 | Bicarbonate (HCO₃⁻/H₂CO₃) |
Intracellular Fluid | ~7.0 | Intracellular Fluid | ~7.0 | Phosphate (H₂PO₄⁻/HPO₄²⁻) |
Cerebrospinal Fluid | 7.4 | Cerebrospinal Fluid | 7.4 | Bicarbonate (HCO₃⁻/H₂CO₃) |
Gastric Fluid | 1.5 - 3.5 | Gastric Fluid | 1.5 - 3.5 | None (strong hydrochloric acid) |
Urine | 4.5 - 8.0 | Urine | 4.5 - 8.0 | Phosphate and ammonia systems |
This table highlights key buffer systems that help maintain pH stability in different body fluids.