Pharmaceutical Excipients and Vehicles

Water as a Vehicle

• Potable water is not permitted for pharmaceutical dosage forms
• Purified water is used for aqueous oral and topical dosage forms
• Sterile water for injection (WFI) is used for parenteral preparations which should be free from dissolved gases.
• Examples include aminophylline injection
• Bacteriostatic water for injection used for multiple use, e.g., benzyl alcohol.

Aromatic Water

• Used as flavoring agents for children
• Examples include almond oil, phenol, glycerol, propylene glycol.
• Use for flavoring and sweetening.
• Internal (parenteral) use;

Otic Use

• Oils, such as castor oil, are used topically
• Coconut oil is used orally
• Wintergreen oil, turpentine oil, and peppermint oil are used for flavoring/perfumes

Alcohol

• Ethyl alcohol used externally for keratolytics, in Psoriasis, or warts.
• Propylene glycol and glycerol used internally and externally as preservatives and sweetening agents

Excipients

• Buffers control pH
• Density modifiers are used in spinal anesthetics
• Isotonicity is important for parenterals, ophthalmics, and nasals
• Viscosity enhancers increase viscosity
• Preservatives slow down bacterial growth
• Antioxidants are reducing agents that help prevent oxidation
• Sweetening agents are used
• Flavors and perfumes add taste
• Coloring agents provide color

Antioxidant

• Reducing agents and chelating agents are used as antioxidants
• Examples include BHT, BHA, ascorbic acid (vitamin C), tocopherol (vitamin E), sodium metabisulfite, and citric acid
• BHT is butylated hydroxy toluene

Sweetening Agents

• Natural sweetening agents include sucrose, glucose, honey and sorbitol, mannitol, and glycerol are used for diabetic patients.
• Synthetic sweetening agents include saccharin, aspartame, and sucralose.

Suspension

• Wetting agents for hydrophobic drugs
• Flocculating agents for suspensions
• Surface-active agents (e.g., Tween 80) are used
• Hydrophilic colloids such as acacia, tragacanth, and bentonite are used
• Solvents like alcohols and glycerin are used
• Structural vehicles such as sodium carboxymethylcellulose are used to suspend or thicken

Liq Dosage Forms

• Syrups (medicated or flavored)
• Elixirs (no need for preservatives, some examples are Dexamethasone or Phenobarbital)
• Linctuses
• Dry powders (e.g., penicillin V or cloxacillin)
• Solutions (e.g., for salicylic acid)
• Lotions
• Liniments (e.g., for methyl salicylate)
• Paints (for topical oral or dental applications, e.g., benzocaine, eugenol).
• Oral Spirits (flavoring agent)

Solutions in Body Cavities

• Rectal solution: e.g., aminophylline, hydrocortisone
• Retention enema
• Evacuation enema: e.g., magnesium sulfate
• Diagnostic enema: e.g., barium sulfate

This quiz covers key concepts related to pharmaceutical excipients, including the roles of various types of water, aromatic agents, and oils in drug formulations. Understand the importance of purity and the specific uses of these substances in different dosage forms. Test your knowledge on both the practical applications and regulatory considerations involved in pharmaceutical preparations.