Maintaining pH balance and electrolyte concentration is essential for human survival and drug stability. This unit explains the principles of acids, bases, and buffers, their role in pharmaceutical systems, and their practical applications in formulations. You’ll also learn about physiological electrolytes, their therapeutic use, and important dental products for oral care.
Acids and Bases in Pharmacy
Acids, bases, and buffers are fundamental to pharmacy because they control the pH of drug formulations. This is critical for ensuring a drug’s solubility, stability, efficacy, and patient comfort. A pharmacist must have a deep understanding of these concepts to formulate and dispense medications safely and effectively.
Acids and Bases in Pharmacy
Acids and bases are defined by their ability to donate or accept protons.
- Acids are proton donors (H+). In pharmaceutical contexts, many drugs are weak acids (e.g., aspirin) and their solubility and absorption are pH-dependent.
- Bases are proton acceptors (OH−). Similarly, many drugs are weak bases (e.g., morphine), and their chemical behavior is highly sensitive to pH changes.
Buffers
A buffer is a solution that resists changes in pH when small amounts of an acid or a base are added. In pharmacy, buffers are indispensable for maintaining the pH of a drug product within an optimal range. They typically consist of a weak acid and its conjugate base or a weak base and its conjugate acid.
Why are Buffers So Important?
- Drug Stability: Many drugs are susceptible to degradation (e.g., hydrolysis or oxidation) at extreme pH values. Buffers protect the drug from breaking down, thus extending its shelf life. For example, some antibiotics are stable only within a specific pH range.
- Drug Solubility: The solubility of many drugs is highly dependent on pH. Buffers are used to maintain a pH where the drug is most soluble, ensuring that the medication remains dissolved throughout its shelf life and is effectively absorbed by the body. For instance, weak acidic drugs are more soluble in basic solutions, while weak basic drugs are more soluble in acidic solutions.
- Patient Comfort: For routes of administration like injections, eye drops, and nasal sprays, the pH of the formulation must be close to the physiological pH of the body fluid at the site of administration to prevent pain, irritation, or tissue damage. The pH of blood is tightly regulated at approximately 7.4.
- Biological Activity: Many enzymes and other biological molecules have a narrow pH range in which they function optimally. Buffers are used in certain formulations to ensure the drug’s activity isn’t compromised.
What are Physiological Electrolytes?
Physiological electrolytes are essential minerals in the body’s fluids and tissues that carry a positive or negative electrical charge when dissolved. They are vital for numerous physiological processes and must be maintained within a very narrow concentration range for the body to function correctly.
Functions of Major Physiological Ions
- Sodium (Na⁺): Maintains osmotic balance, nerve function.
- Potassium (K⁺): Controls muscle contraction, cardiac rhythm.
- Calcium (Ca²⁺): Bone health, blood clotting, neuromuscular function.
- Chloride (Cl⁻): Maintains osmotic pressure, acid-base balance.
Dental Products and Their Role in Oral Health
Dental products are specialized formulations and tools used for maintaining oral hygiene and treating various oral health conditions. They play a critical role in preventing diseases like tooth decay, gum disease, and bad breath.
Key Dental Products and Their Roles
1. Toothpaste
Toothpaste is a dentifrice, a substance used with a toothbrush to clean teeth. It’s a cornerstone of oral hygiene.
- Abrasives: Ingredients like calcium carbonate and hydrated silica physically scrub away plaque and food debris.
- Fluoride: Compounds such as sodium fluoride or stannous fluoride are crucial for preventing cavities. Fluoride strengthens tooth enamel, making it more resistant to acid attacks from bacteria.
- Detergents: Foaming agents like sodium lauryl sulfate help to loosen and remove debris.
- Therapeutic agents: Toothpastes can also contain ingredients for specific needs, such as potassium nitrate for sensitive teeth, or triclosan for its antibacterial properties.
2. Mouthwash
Mouthwash is a liquid solution used to rinse the mouth. It complements brushing and flossing but doesn’t replace them.
- Antiseptic agents: Ingredients like chlorhexidine, cetylpyridinium chloride (CPC), and eucalyptol help kill bacteria that cause plaque, gingivitis, and bad breath.
- Fluoride: Some mouthwashes contain fluoride to provide an extra layer of protection against cavities.
- Freshening agents: Menthol and other flavorings help to freshen breath.
3. Dental Floss and Interdental Cleaners
These tools are used to remove plaque and food particles from between teeth, where a toothbrush can’t reach.
- Dental Floss: A thin thread used to clean the tight spaces between teeth and along the gumline.
- Interdental Brushes: Small brushes designed to clean larger gaps between teeth, especially useful for people with bridges, braces, or implants.
- Water Flossers: Devices that use a high-pressure stream of water to remove debris from between teeth and below the gumline.
4. Disclosing Tablets
These tablets contain a harmless dye that stains any remaining plaque on the teeth after brushing. They are a valuable tool for showing you where you’re missing spots, helping you improve your brushing technique.
FAQs – Acids, Bases, Buffers & Electrolytes
1. Why are buffers important in pharmaceutical formulations?
They help maintain a constant pH, ensuring drug stability and preventing irritation when administered.
2. What is isotonicity and why is it important?
Isotonicity prevents cell damage and pain when solutions are injected or applied to sensitive tissues like eyes.
3. Why is ORS used in dehydration?
ORS restores fluid and electrolyte balance, preventing complications from severe water loss.
4. How does fluoride prevent dental caries?
Fluoride strengthens tooth enamel by forming fluorapatite, making it resistant to acid attacks.
5. What happens if the body’s pH balance is disturbed?
It can lead to acidosis or alkalosis, which can affect enzyme activity and cell function.