When we think about medicines, tablets and syrups often come to mind. But behind the scenes, invisible chemical systems like buffers and electrolytes keep the body balanced and medicines stable. Meanwhile, dental products—something as ordinary as toothpaste—are deeply rooted in pharmaceutical chemistry. Unit 2 of pharmaceutics brings these hidden yet vital systems into the spotlight.
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Acids, Bases, and Buffers – Keeping Balance in Check
Understanding Buffers
In chemistry, a buffer is a solution that resists sudden changes in pH when small amounts of acid or base are added. This is crucial not only in laboratories but also inside the human body, where enzymes and biological reactions demand a stable environment.
The Henderson–Hasselbalch equation provides a mathematical way to calculate the pH of buffer solutions. More importantly, buffer capacity measures how well a buffer can resist changes in pH, a factor critical in pharmaceutical formulations.
Buffers in Pharmaceuticals
Many drugs are unstable in extreme pH conditions. Buffers stabilize them, ensuring potency and extending shelf life. For instance, eye drops are buffered to remain gentle on the eye while nasal sprays are adjusted to match the body’s natural environment.
Stability and Isotonicity
Pharmaceutical buffers must also remain stable over time, resisting decomposition. In addition, when medicines are injected or applied to sensitive tissues, they must be isotonic—that is, having the same osmotic pressure as body fluids.
Buffered isotonic solutions are essential in injections, eye drops, and intravenous infusions.
Tonicity measurements rely on freezing point depression or osmotic pressure comparisons.
If a solution is not isotonic, methods such as the cryoscopic method, sodium chloride equivalent method, or the White–Vincent method are used to adjust it, ensuring safety and comfort for patients.
Major Extra- and Intracellular Electrolytes – The Body’s Chemical Electricity
Electrolytes are minerals that carry electric charge in body fluids, regulating countless physiological functions.
Functions of Major Ions
Sodium (Na⁺): Maintains fluid balance and nerve transmission.
Potassium (K⁺): Essential for muscle contraction and heart function.
Calcium (Ca²⁺): Critical for bones, blood clotting, and nerve signaling.
Chloride (Cl⁻): Balances fluids and aids digestion in the stomach.
Bicarbonate (HCO₃⁻): Key in maintaining acid-base balance.
Replacement Therapy in Action
When illness, dehydration, or surgery causes electrolyte loss, replacement becomes life-saving:
Sodium chloride (common salt): Restores hydration and plasma volume.
Potassium chloride: Prevents and treats hypokalemia (low potassium).
Calcium gluconate: Used in calcium deficiencies, hypocalcemic tetany, or as a cardiac stabilizer.
Oral Rehydration Salts (ORS): A simple yet powerful mixture of salts and glucose, ORS has saved millions of lives worldwide by treating dehydration caused by diarrhea.
Physiological Acid–Base Balance
The body’s pH is tightly regulated around 7.35–7.45. Buffers, lungs, and kidneys all work together to maintain this balance. A slight shift can lead to acidosis or alkalosis, conditions that can threaten life. This makes electrolytes and buffer systems central to clinical medicine.
Dental Products – Everyday Chemistry for Oral Health
While buffers and electrolytes work silently inside the body, pharmaceutical chemistry is equally important in something we use every morning: dental products.
Dentifrices: More Than Just Toothpaste
Dentifrices (tooth-cleaning agents) include toothpastes and tooth powders. Their role goes beyond cleaning; they also prevent cavities, strengthen enamel, and freshen breath.
Fluoride and Dental Caries
Dental caries (tooth decay) is caused by acids produced by bacteria that erode enamel. Fluoride helps prevent this by strengthening enamel and making it resistant to acid attack. Sodium fluoride is widely added to toothpastes, while some communities add fluoride to drinking water as a preventive health measure.
Desensitizing Agents
Tooth sensitivity is another common dental problem. Desensitizing agents, such as strontium chloride or potassium nitrate, work by blocking nerve transmission in exposed dentin, reducing discomfort.
Common Pharmaceutical Ingredients in Dental Products
Calcium carbonate: Acts as a mild abrasive and neutralizes acids.
Sodium fluoride: Provides anti-caries protection.
Zinc eugenol cement: Used by dentists as a restorative and protective material, valued for its soothing effect on dental pulp.