Pharmaceutical Solutions and Drug Delivery Methods

Pharmaceutical solutions

Liquid preparations with one or more chemical substances dissolved in a suitable solvent or mixture of mutually miscible solvents.

Examples of pharmaceutical solutions

Oral solution, ophthalmic solution, topical solution.

Syrups

Aqueous solutions containing a sugar or sugar substitute.

Elixirs

Sweetened hydroalcoholic solutions, usually flavored for palatability.

Spirits

Solutions of aromatic materials in alcohol.

Aromatic waters

Solutions of aromatic materials in water.

Tinctures or fluid extracts

Solutions made by extracting active constituents from crude drugs using alcohol or hydroalcoholic solvents.

Advantage of drug solutions over suspensions or solid dosage forms

More rapid absorption from the gastrointestinal tract.

Techniques to speed up solute dissolution

Heating, reducing particle size, using solubilizing agents, and agitation.

Typical composition of oral rehydration solution

Na⁺ (45 mEq), K⁺ (20 mEq), Cl⁻ (35 mEq), Citrate (30 mEq), Dextrose (25g/L).

Types of syrups

Non-medicated (e.g., cherry syrup) and medicated (e.g., cough syrup).

Main advantage of syrups for pediatric use

Masks bitter or unpleasant taste of drugs.

Sugars or substitutes used in syrups

Sucrose, dextrose, sorbitol, glycerin, propylene glycol.

Examples of preservatives in syrups

Benzoic acid, sodium benzoate, parabens, alcohol.

Common flavorants in syrups

Volatile oils (e.g., orange oil), vanillin.

Common colorants used in syrups

Green for mint, brown for chocolate, etc.

Main components of elixirs

Solvent (alcohol/water), sweetener, flavoring agent, colorant, preservative.

Why additional preservatives are often unnecessary in elixirs

Because alcohol (10-12%) acts as a preservative.

How elixirs are prepared

By dissolving alcohol-soluble and water-soluble ingredients separately and then mixing with agitation.

Examples of medicated elixirs

Phenobarbital elixir, theophylline elixir, digoxin elixir.

Dosage form with the greatest oral absorption

Oral solution.

Not used as a preservative in syrups

Glycerin.

Advantages of nasal drug delivery

Large surface area, no first-pass metabolism, quick absorption, CNS delivery potential.

Limitations of nasal drug delivery

Irritation, nasal filtration limiting bioavailability.

Types of nasal formulations

Drops, solution sprays, powders, gels, emulsions/ointments, microspheres.

Advantage of nasal powders

Good for unstable drugs, improved compliance.

Advantage of nasal gels

Longer contact time and reduced leakage.

Microspheres used for in nasal delivery

Enhance absorption due to mucoadhesive properties.

Function of nasal microvilli

Increase surface area for absorption.

Purpose of otic drug delivery

To remove earwax or treat local infections.

Common preparations in otic drug delivery

Unsaturated solutions, sometimes suspensions or ointments.

How lipophilic solids are dissolved for otic delivery

Heating, size reduction, solubilizers, or agitation.

Sterilization methods for otic preparations

Physical (heat, UV), chemical (bactericides), mechanical (filtration).

Examples of cerumen-removal otic solutions

Triethanolamine oleate in propylene glycol, carbamide peroxide in glycerin.

Examples of antibiotic otic preparations

Chloramphenicol, colistin sulfate, polymyxin B sulfate.

Examples of anti-inflammatory/analgesic otic agents

Dexamethasone sodium, hydrocortisone.

Active ingredient in Auralgan® and its use

Benzocaine + antipyrine for cerumen removal and otitis media.

Active ingredient in Debrox® and its use

Carbamide peroxide for cerumen removal.

Active ingredient in Ciprodex® and its use

Ciprofloxacin + dexamethasone for ear infections.

Active ingredient in Floxin Otic® and its use

Ofloxacin for otitis externa and media.