Liquid Dosage Forms - Solutions

Question 1

What is a solute

Answer 1

Dissolved agent in a solution

Question 2

What is a solvent

Answer 2

Component in which the solute is dissolved

Question 3

What is dissolution

Answer 3

The process of a solid going into solution

Question 4

What is a solution

Answer 4

Thermodynamically stable, homogeneous system made of 2 or more components

Question 5

What is a pharmaceutical solution

Answer 5

Liquid preparations that contain 1 or more substances dissolved in a suitable solvent or mixture of mutually miscible solvents

Question 6

What is a saturated solution

Answer 6

Contains the max amount of solute that the solvent will accommodate at room temp. and pressure

Question 7

What is a supersaturated solution

Answer 7

Contains a larger amount of solute than the solvent can normally accommodate at that temp. and pressure

Question 8

What is drug solubility

Answer 8

Quantity of a drug maintained in solution at a given temp. and pressure expressed as the mL of solvent required to dissolve 1g of the drug

Question 9

Dissolution process involves:

Answer 9

1. Breaking of solute bonds
2. Separation to provide space in the solvent for the solute
3. Interaction between solvent and solute molecule/ion

Question 10

What are the factors affecting dissolution

Answer 10

• pH
• Temperature
• Pressure
• Particle size
• Agitation
• Physical and chemical attributes of the solvent and the solute

Question 11

Considerations for solute-solvent interactions

Answer 11

• Acceptability of solvent
• Compatibility of 2 or more solutes
• Chemical stability of solute in solution
• Effects of physical conditions
• Are additives required

Question 12

Solvents criteria

Answer 12

• Completely dissolve the drug and other solid ingredients at the desired concentration -> homogeneous
• Non toxic and safe for injection or topical application
• Be aesthetically acceptable to the patient in terms of appearance, aroma, texture, and/or taste

Question 13

Types of solvent

Answer 13

• Water - drinking water, purified water, water for injection
• Alcohol, USP: Ethyl alcohol, ethanol - miscible with water, used as a solvent and excipient in the formulation of oral pharmaceutical products, able to dissolve many water insoluble ingredients and used as antimicrobial preservative
• Dilute alcohol, NF - mixture of equal volumes of alcohol, USP and purified water, USP
• Rubbing alcohol - 70% ethyl alcohol by volume in water, denaturants, colorants, perfume oils and stabilizers.
• Glycerin, USP - clear syrupy, viscous liquid with sweet taste, miscible with both water and alcohol, used as preservative and stabilizer
• Isopropyl rubbing alcohol - contains 70% by volume of isopropyl alcohol
• Propylene glycol, USP - viscous liquid miscible with both water and alcohol

Question 14

How to obtain purified water from drinking water

Answer 14

• Filtration
• Passing through activated carbon beds
• Addition of chemical additives/water softeners
• Deionisation and electrodialysis - remove cations and anions
• Reverse osmosis, ultrafiltration and distillation

Question 15

Classify solutions based on

Answer 15

• Solute molecular size - micromolecular (MW<10,000)/macromolecular(MW>10,000)
• Solution’s use - oral, ophthalmic, otic, topical
• Composition/use - aqueous solutions (syrups: solutions contain sweeteners, aromatic water: solutions of volatile oils, mucilages: solutions of vegetable oils in water, aqueous acids), nonaqueous solutions (elixir, tinctures, spirits, liniments, collodion)

Question 16

Considerations for solutions

Answer 16

• Unsaturated -> avoid precipitation due to changes in temp
• Strength
• Solutes differ in their solubilities: To increase dissolution -> use heat, decrease particle size, enhancers, agitation, etc.
• Oral adult solutions may need to be diluted to a pediatric form
• Some medicinal agents (e.g. antibiotics) have insufficient stability in aqueous solution and are marketed as dry mixtures for solutions

Question 17

Applications for solutions

Answer 17

• Vehicles for oral, parenteral, topical, otic, ophthalmic, and nasal products
• Flavorings, buffers, preservatives, and suspending agents for a variety of liquid dosage forms
• Components of extemporaneously prepared products
• Test solutions used in analysis of pharmaceutical products of all types
• Dry mixtures for solutions need to be mixed with water for oral administrations

Question 18

Definition of syrup

Answer 18

A concentrated or nearly saturated solution of sucrose or sucrose substitute in water

Question 19

Types of syrup

Answer 19

• Simple syrup: contain only sucrose and purified water
• Nonmedicated/flavoring syrups: contain pleasantly flavored substances and employed as a pleasant tasting vehicle for therapeutic agents
• Medicinal syrups - contain therapeutic compounds

Question 20

Components of syrup

Answer 20

• purified water
• medicinal agents
• sugar: sucrose or sugar substitute to provide viscosity, sweetness, mask the taste and prevent drug irritation
• antimicrobial preservatives: benzoic acid, sodium benzoate, Methylparaben, propylparaben
• flavorants: volatile oils, vanillin
• colorants: green-mint, brown-chocolate
• others: special solvents, solubilizers, stabilizers and thickeners

=> compatibility is impt - no interaction/reaction between the ingredients

Question 21

Preparation of syrup

Answer 21

• Solution with heat: Problem: inversion of sugar due to hydrolysis
• Solution with agitation but without heat: use of mixers and agitators
• Addition of sucrose to a medicated liquid or to a flavoured liquid
• Percolation: filtration of a liquid for extraction

Question 22

Sources of sweeteners

Answer 22

• Sugars: sucrose
• Non-sugar polyols: sorbitol, glycerin, propylene glycol, mannitol - polyols can provide viscosity and may act as cosolvents and preservatives
• Non-nutritive artificial sweeteners: aspartame, saccharin -> do not impart viscosity

Question 23

Definition of elixirs

Answer 23

Clear, sweetened hydroalcoholic solutions intended for oral use and are usually flavored to enhance their palatability; can be medicated/non-medicated

Question 24

Alcoholic content of elixirs

Answer 24

5-40%

Question 25

Preparation of elixirs

Answer 25

- Simple solution with agitation and/or by admixture of 2 or more liquid ingredients - Alcohol soluble and water soluble components are dissolved separately in alcohol and purified water respectively -> 2 mixtures - Aqueous solution added to the alcoholic solution -> mixture made to the specific volume by the given solvent - alcohol added to keep all contents in solution - addition of aqueous solutions may cause turbidity/separation by lessening alcohol concentration

Question 26

Elixirs compared to syrups

Answer 26

- Less sweet and viscous - Less effective in masking the taste of medicinal agents - Dissolve both water soluble and alcohol soluble materials - More stable and easier to prepare - Preferred

Question 27

Definition of spirits

Answer 27

Alcoholic/hydroalcoholic solutions of volatile substances (volatile oils) and prepared by simple solution, solution by maceration/distillation

Question 28

Alcoholic content of spirits

Answer 28

60%

Question 29

Spirits used as

Answer 29

flavoring or therapeutic agents

Question 30

Definition of tinctures

Answer 30

Alcoholic/hydroalcoholic solutions prepared from vegetable/chemical substances generally extracted by maceration/percolation - must be closed tightly in light resistant containers

Question 31

Alcoholic content of tinctures

Answer 31

15-80%

Question 32

Definition of collodions

Answer 32

Liquid preparations containing nitrocellulose pyroxylin in a solvent mixture of alcohol and ethyl ether

Question 33

Uses of collodions

Answer 33

provide topical protectives or as a topical drug vehicle

Question 34

Definition of liniments

Answer 34

Alcoholic/oleaginous solutions or emulsions of various substances intended for external application to skin, generally with rubbing

Question 35

Examples of tinctures

Answer 35

vanilla tincture USP, iodine tincture USP