Liquid Dosage Forms

Question 1

Liquid dosage forms

Answer 1

Oral solutions, syrups, elixirs and tinctures, topical aqueous solutions, rectal solutions, miscellaneous solutions, non-aqueous solutions, extraction methods

Question 2

These points should be considered when compounding a pharmaceutical solution:

Answer 2

Solubility
Stability
Physical/Chemical Interaction

Question 3

How can you alter solubility?

Answer 3

Solubilizing agents
Different salt forms
Alteration of the pH
Adding a co-solvent

Question 4

How to alter the rate of solution?

Answer 4

Particle Size

Extent of Agitation

Question 5

Methods of water purification

Answer 5

Distillation: makes distilled water
Ion exchange: makes deionized water
Reverse osmosis: cross flow membrane filtration

Question 6

Ethanol

Answer 6

Miscible with water (hydroalcoholic)
Antimicrobial effects in external application
Volatile, flammable
Restricted use in OTC products

Question 7

Types of ethanol Preparations

Answer 7

Alcohol USP (94.9-96%v/v ethanol–primary solvent for organic compounds )

Dehydrated Alcohol USP (99.5% ethanol v/v)

Diluted Alcohol NF: equal vol of Alcohol USP and water (49%v/v - 3% less final vol)

Alcohol, Rubbing USP (70%v/v for external use)

• Bitter substances: denatonium benzoate or sucrose octa-acetate)
• Denaturant

Question 8

Pharmaceutical solvents

Answer 8

Glycerin USP

• miscible with water and alcohol
• stabilizer, preservative, wetting agent, sweetener, auxiliary solvent
• external or internal use

Isopropyl Alcohol
-use externally for skin rubbing, or topical vehicle, or for injection preparations and skin disinfecting

Propylene Glycol
-Frequently substituted for glycerin

Question 9

Dry mixture for solution

Answer 9

Drug powders used for better stability
Drug powder or granule form is reconstituted with purified water immediately before dispensing
Stores in fridge for 7-14 days

Question 10

Oral Solutions

Answer 10

oral rehydration solutions
available in liquid or powder (ex Pedialyte)
Do not mix with milk or fruit juices

Question 11

Syrup

Answer 11

Concentrated aqueous preparation of sugar or sugar substitutes (60-80%) sucrose; sorbitol; glycerin, methylcellulose
Resistant to antimicrobial growth
Medicated or non medicated
Commonly used as vehicles for compounding
Gives pleasant taste to disagreeable tasting drugs
Antitussives and antihistamines

Question 12

Elixirs

Answer 12

Clear, sweetened hydroalcoholic solutions intended for oral use and are usually flavored to enhance palatability
Medicated elixirs: less sweet and less viscous than syrup and uses alcohol to increase drug solubility
Non-medicated elixirs for compounding
Advantages: flexibility and ease of dose administration in patients with difficulty swallowing solid forms

Question 13

Tinctures

Answer 13

Alcoholic or hydroalcoholic (15-80%) solutions (extracts) from vegetable or chemical materials
Must be tightly stoppered and not exposed to excessive temperature, store in light resistant containers

Question 14

Types of Tinctures

Answer 14

Oral- Opium tincture (Laudanum)
Topical- compound benzoin tincture (skin protectant)
Iodine tincture (local anti-infective)

Question 15

Topical aqueous solutions

Answer 15

Aluminum acetate topical solution (Burow’s solution): astringent

Calcium hydroxide topical solution (lime water)

Hydrogen peroxide topical solution

Povidone iodine topical solution: iodine-polyvinylpyrrolidone complex solution in water, nonirritating antiseptic solution

Coal tar topical solution (an alcoholic solution): 20% coal tar, 5% polysorbate 80, ~80% ethanol

Question 16

Rectal Solutions

Answer 16

• Retention Enemas: for local effects and systemic absorption
• Evacuation Enemas: Disposable plastic squeeze bottles containing monobasic and dibasic sodium phosphate as a saline laxative)

Question 17

Miscellaneous Solutions

Answer 17

Aromatic waters: clear, aqueous solutions saturated with volatile oils or other aromatic/volatile substances
Spirits: alcoholic solutions of volatile substances, generally high alcoholic concentration (>60%)
Diluted acids

Question 18

Non-Aqueous Topical Solutions

Answer 18

Liniments, alcoholic or oleaginous solutions, intended to be rubbed on the skin (label: for external use only)
Collodion:
4% pyroxylin in alcohol/ether (3:1)
Volatile and flammable
External use only
Flexible collodion: 
Collodion with 2% camphor, 3% castor oil

Question 19

Extraction Methods

Answer 19

Extraction: withdrawal of desired constituents from crud drugs by selected solvents, in which the desired constituents are soluble
Menstruum: the solvent (or vehicle)
Extractive: extracted constituents (the product)
Marc: the residue (Marc = Crude drug materials – Extractives)

Maceration: soak; leach by stand in solvent (like tea bag; vanilla extracts)

Percolation: leach by running solvent– extract by slow passage of a solvent through a column of drug (like coffee maker)