Pharmaceutical Formulation Basics

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Questions and Answers

Which of the following substances are commonly used as buffers in pharmaceutical formulations?

Carbonates and phosphates (correct)

Carbomer and BHA

Sorbitol and glycerol

Sodium chloride and sucrose

What purpose do isotonicity modifiers serve in drug formulations?

Increase viscosity for better retention

Mitigate pain and irritation in mucous membranes (correct)

Help maintain pH stability

Act as antioxidants

Which of the following agents is known to enhance the viscosity of pharmaceutical formulations?

Sucrose

Sodium metabisulphite

Parahydroxybenzoic acid esters

Hydroxyethylcellulose (HEC) (correct)

Which sweetening agent is specifically noted for being cariogenic?

Sucrose Signup and view all the answers

What is a significant drawback of artificial sweeteners like aspartame?

Bitter or metallic aftertaste Signup and view all the answers

What is the primary purpose of using colours in product preparation?

To improve the attractiveness of the product and enable easy identification. Signup and view all the answers

Which type of liquid preparation is specifically designed for skin application without friction?

Lotions Signup and view all the answers

What type of product is used for local administration in the external auditory canal?

Ear preparations Signup and view all the answers

Which component is commonly found in eye preparations?

Sterile liquids Signup and view all the answers

What distinguishes elixirs from other oral liquid preparations?

They are clear, sweetened, hydroalcoholic solutions. Signup and view all the answers

What is the primary function of irrigation solutions?

For the cleansing of body cavities and wounds. Signup and view all the answers

What defines mixtures in oral liquids compared to draughts?

Mixtures can be solutions or suspensions, while draughts are given in large doses. Signup and view all the answers

Which of the following is NOT a component used in ear preparations?

Aromatic spirits Signup and view all the answers

What type of product would typically be classified as a liniment?

Massage products containing counterirritants Signup and view all the answers

What is the characteristic feature of rectal preparations such as enemas?

They can come as aqueous or oily solutions for rectal use. Signup and view all the answers

Study Notes

Formulation Additives

Buffers enable solutions to resist pH changes when acid or alkali is added.
Choosing a buffer considers pH, buffering capacity, compatibility, and toxicity.
Examples of buffering agents include carbonates, citrates, gluconates, lactates, phosphates, and tartrates.
Buffers are crucial in injections, eye drops, and nasal drops to maintain a pH of 7.4 and avoid irritation.
Optimal stability, solubility, and bioavailability are linked to the physiological pH.

Isotonicity Modifiers

Isotonicity modifiers are added to injections and large-volume ophthalmic solutions to prevent pain, irritation, and damage to mucous membranes.
These modifiers are added after other ingredients.
Dextrose and sodium chloride are commonly used isotonicity modifiers.

Viscosity Enhancement

Viscosity enhancers help liquids remain on the skin or in the eyes.
These include low concentrations of gelling agents like povidone, hydroxyethylcellulose (HEC), and carbomer.

Preservatives

Preservatives can be chosen based on their adsorption onto the container and efficiency compared to pH.
Parahydroxybenzoic acid esters or micelles are examples of preservatives.

Reducing Agents and Antioxidants

Reducing agents and antioxidants prevent pharmaceutical product decomposition through oxidation.
Examples include sodium metabisulphite, BHA, and BHT.

Sweetening Agents

Low molecular weight carbohydrates are used as sweeteners.
Sucrose is colorless, soluble, and stable over a pH range of 4-8.
Sucrose increases viscosity resulting in a pleasant mouthfeel and masks salty or bitter tastes.
Sucrose can soothe throat membranes, especially in antitussive preparations.
A disadvantage of sucrose is its cariogenic property.
Other polyhydric alcohols, such as sorbitol, mannitol, and glycerol, serve as sweeteners, particularly for those with diabetes.
Artificial sweeteners such as sodium or calcium salts of saccharin (E954) are highly soluble in water and chemically and physically stable.
Aspartame (E951) is another artificial sweetener but has a bitter or metallic aftertaste. It is often combined with sugars.

Flavors and Perfumes

Flavors and perfumes are used when a product has an unpleasant taste.
They enhance palatability, particularly in pediatric products and liquid products.
Natural sources include fruit juices, aromatic oils (e.g., peppermint, lemon), and herbs/spices.
Synthetic flavors are often cheaper, more readily available, and more stable. They are commonly used in solutions (aq/alc) and powders.
Suitable masking flavors for various tastes are also listed.

Colors

Colors enhance the attractiveness of products, compatible with flavor.
Colors improve product identification.

Liquid Preparations for Cutaneous Application

Lotions: Applied to skin without friction. Often contain humectants or alcohol.
Liniments: Massaged into skin. Often contain counterirritants (e.g., methyl salicylate or camphor).
Paints: Applied to skin or mucous membranes in small amounts (e.g., small brushes). Solvent evaporates, leaving a film with the active agent. Viscosity modifiers ensure prolonged skin contact.

Ear Preparations

Ear preparations are also known as otic or aural products.
They are simple solutions of drugs in a suitable vehicle for local use.
Vehicles include water, glycerol, propylene glycol or alcohol/water mixtures.
Applications include drops, sprays, or washes.
Ear preparations are used for antibiotics, antiseptics, cleansing solutions, and wax softeners.

Eye Preparations

Eye preparations are small-volume sterile liquids.
They are applied to the eyeball or conjunctival sac to achieve a local effect.

Irrigation Solutions

Irrigation solutions are large-volume aqueous-based solutions for cleaning body cavities and wounds.
These solutions must be isotonic.

Nasal Products

Nasal products are not further detailed.

Oral Liquids (Elixirs)

Elixirs are clear, sweetened, hydroalcoholic solutions for oral use, often flavored for palatability.
Types include non-medicated (vehicles) and medicated (therapeutic effect).

Oral Liquids (Mixtures and Draughts)

Mixtures are aqueous preparations, either solutions or suspensions, with a short shelf-life.
Draughts are mixtures with one or two large doses (around 50 mL).

Rectal Preparations (Enemas)

Enemas are aqueous or oily solutions, emulsions, or suspensions administered rectally.
Enemas are used for cleansing, diagnostic, or therapeutic purposes.

Intermediate Products (Aromatic Waters and Spirits)

These are aqueous solutions of volatile materials.
Primarily used for flavoring.
Not often administered directly. Examples include peppermint and anise water.
Concentration is usually 1:40.

Extarcts, Infusions, and Tinctures

Extracts, infusions, and tinctures are concentrated solutions of active principles from plants or animals.
Infusions are made without heat and use 25% alcohol.
Extracts are concentrated using evaporation.
Tinctures are weak alcoholic extracts.

Syrups

Syrups are concentrated solutions of sucrose or other sugars.
Medicaments and flavorings are often added to them.
Examples include Codeine Phosphate Syrup and Orange Syrup.
Syrups resist bacterial growth due to high sugar content (85%), working through osmosis.
Lower sugar concentrations may use polyhydric alcohols (sorbitol, glycerol, propylene glycol) as these create osmotic pressure.
Problems can include crystallization of sugar, so polyhydric alcohols or invert syrup are used as alternatives.

Manufacture of Solutions

Solutions are made on small or large scales using mixing vessels with agitation.
Solutes are added to solvents for complete dissolution, potentially using heat or size reduction for faster mixing.
Easily volatile or heat-sensitive materials are handled with careful cooling and to prevent adsorption issues.
Solutes in low concentrations can be predissolved.

Stability of Solutions

Chemical and physical factors affect solution stability.
Clarity, color, odor, taste, and viscosity of the solution should be assessed.
Clarity can be checked visually or by optical density after stirring.
Color is assessed visually and spectrophotometrically.
Flavors and fragrances should be checked using chromatographic methods.

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Description

This quiz covers essential concepts in pharmaceutical formulation, including buffers, isotonicity modifiers, and viscosity enhancers. Learners will explore the importance of maintaining pH and stability in injections and ophthalmic solutions. Test your knowledge on key ingredients and their roles in ensuring patient safety and product effectiveness.