Pharmaceutical Dosage Forms: Liquid Solutions

Pharmaceutical Dosage Forms/Theory - Lecture 6: Liquid Dosage Forms: Solution and Orally Administered Solutions

• Solutions are homogenous, one-phase systems composed of two or more components. A solution is comprised of a solute (solid, liquid, or gas) dissolved in a solvent.
• Commonly, solutions are in liquid form.
• Advantages of using solutions include:
  • Easy to swallow, particularly for pediatric and geriatric patients
  • Rapid onset of action, as dissolved drugs are immediately available for absorption in the gastrointestinal tract (GIT)
  • Greater bioavailability than solid dosage forms
  • Avoid irritation of the gastrointestinal tract due to immediate absorption
• Disadvantages of using solutions include:
  • Bulkiness and difficulty in transportation
  • Difficulty masking unpleasant tastes or odors
  • Requiring an accurate measuring tool for dosage
  • Lower stability and shorter shelf life compared to solid dosage forms
  • Need for preservatives.

Different Types of Solutions for Different Routes of Administration

• Ear preparations (e.g., Garamycin ear drops)
• Liquids for cutaneous application (e.g., lotions, liniments)
• Eye preparations (e.g., chloramphenicol eye drops)
• Mouthwashes and gargles (e.g., Chlorhexidine mouthwash)
• Nasal products (e.g., Xylometazoline nasal spray)
• Oral liquids (e.g., solutions, elixirs, suspensions, emulsions)
• Rectal preparations (e.g., enemas, douches)
• Parenteral products (e.g., Normal Saline, Glucose Saline)

Common Excipients in Pharmaceutical Solutions

• Buffers: Maintain the pH of the solution. Examples include acetate, citrate, and phosphate.
• Sweetening agents: Enhance flavor, mask bitterness, and improve palatability. Examples include sucrose, liquid glucose, glycerol, sorbitol, saccharin sodium and aspartame.
• Viscosity-Enhancing agents: Affect the pourability and accurately support dose measurements; examples include Methylcellulose, Hydroxypropyl methylcellulose, Carbomer, Polyvinylpyrrolidone, Sodium Carboxylmethylcellulose.
• Antioxidants: Enhance the stability of the active pharmaceutical ingredient (API) against chemical degradation by oxidation. Examples include sodium sulfite, sodium metabisulfite, sodium formaldehyde sulfoxylate, and ascorbic acid.
• Preservatives: Prevent or slow the growth of microorganisms. Examples include benzoic acid and salts, sorbic acid and salts, and alkyl esters of parahydroxybenzoic acid (parabens).

Homework 01

• Students are tasked with collecting information and images of 10 pharmaceutical products in solution dosage form from a local pharmacy.
  • 4 products for oral administration
  • 2 products for intravenous (IV) use
  • 2 products for topical use
  • 1 product for eye application
  • 1 product for ear application

Choice of Solvent

• Aqueous solutions: Water is the most common solvent used in pharmaceuticals due to its physiological compatibility and lack of toxicity.
• Non-aqueous solutions: Used when the drug is unstable in an aqueous system. A different solvent must be selected.

Pharmaceutical Ingested Oral Solutions

• The formulation of oral solutions is designed for administration to the gastrointestinal tract, which results in systemic absorption of the therapeutic agent.

Oral Syrups

• Concentrated aqueous solutions often containing sugar (or sugar substitutes) and flavoring agents. Examples include cherry syrup, cocoa syrup, and raspberry syrup.
• Simple syrup (Non-medicated syrup): Aqueous solution comprising 85% sucrose.
• Medicated syrup: Simple syrup with added therapeutic agents.

Major Components of Syrups

• Purified water
• Sweeteners (sucrose, artificial sweeteners)
• Preservatives
• Flavors
• Colors
• Viscosity-modifying agents

Oral Elixirs

• Clear, hydro-alcoholic solutions formulated for oral use.
• Alcohol concentration is unique to each formulation to ensure sufficient antimicrobial properties and solubility.
• Typical components include: purified water, alcohol, co-solvents, sweetening agents, flavors, and colors.
• Preservative amounts are less crucial given the alcohol within these formulations.

Examples of Medicated Syrups

• Analgesics
• Antipyretics
• Antiemetics
• Antihistamines
• Antibiotics
• Antivirals
• Antitussives (cough suppressants)
• Expectorants
• Mucolytics
• Bronchodilators
• Fecal softeners

Pharmaceutical Solutions for the Oral Cavity (Mouthwashes and Gargles)

• Mouthwashes and gargles: Designed to treat infections and inflammations of the oral cavity.
• Gargles: Concentrated solutions used in the posterior region of the mouth to treat throat infections.
• Gargles are usually antimicrobial, astringent or for soothing sore throats.

Mouthwashes

• Medicated liquids for cleansing the oral cavity and treating mucous membranes
• Fluoride mouthwashes: Contain sodium fluoride to strengthen teeth and prevent decay.
• Cosmetic mouthwashes: Primarily used to mask bad breath.
• Antiseptic mouthwashes: Contain chlorhexidine to combat bacterial infections and are suitable for individuals with oral infections
• Analgesic mouthwashes: Contains anesthetic substances such as Lidocaine to relieve pain.

This quiz focuses on the theory of liquid dosage forms, specifically solutions used in pharmaceuticals. It covers the composition, advantages, and disadvantages of orally administered solutions, highlighting their impact on patient care and drug absorption. Test your knowledge on the essentials of liquid dosage forms and their application in medication.