Buffers in Pharmaceutical and Biological Systems

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.

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	Buffer System
Blood Plasma	7.35 – 7.45	Bicarbonate (HCO₃⁻/H₂CO₃)
Intracellular Fluid	~7.0	Phosphate (H₂PO₄⁻/HPO₄²⁻)
Cerebrospinal Fluid	7.4	Bicarbonate (HCO₃⁻/H₂CO₃)
Gastric Fluid	1.5 – 3.5	None (strong hydrochloric acid)
Urine	4.5 – 8.0	Phosphate and ammonia systems