Solution Excipients Flashcards by Niamh M

Excipient Outline

Everything in dosage form except the intentionally therapeutically active substance

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Excipient Specification Outline

Regulatory documents outlining the chemical nature and degradation potential of an excipient. Done by regulatory bodies and pharmacopeia labs

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Ideal Excipient Outline

Chemically and Physically stable, low microbial content, compatible with drug + other excipients, packaging compatibility, non-toxic, inexpensive, palatable and easy to process

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Excipient Sources Outline

Natural, semi-synthetic and synthetic

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Excipient Natural Sources

Mineral oil (petroleum distillation and paraffin wax), water and surfactants (lecithin-egg yellows-emulsifiers

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Excipient Semi-synthetic Sources

cellulose derivatives (gelling agents) and pegylated coconut oil (emulsifiers)

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Common Solution Excipients

Solvents, solubility/permeability enhancers, antimicrobrial stabilisers, chemical stabilisers, physical stabilisers, palatability enhancers and processing enhancers

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Solvent Outline

A substance that dissolves another to produce a solution. Water is most common (non-toxic even in high conc and absorbs a lot of ions).

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Grades of Water Outline

Purified, Highly Purified, Water for injection and sterilised water for injection

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Cosolvents Outline

Water miscible liquid, increases solvents lipophilicity

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Cosolvent Considerations

Toxicity, irritancy, sensitising potential (tissue damage over time), flammability, cost, stability, compatibility and route of admin (eg external = greater irritancy tolerance)

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Ethanol as a Cosolvent

Route: oral, topical and paraenteral. Cools during evapouration. Only used in adults (children don’t have alcohol dehydrogenase), drowsy effects

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Propylene Glycol Outline

Polyhydric (2 OH groups) alcohol. Oral, topical, parenteral and octic routes

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Glycerol Outline

3 hydroxyl groups per alcohol molecule. Route: oral, rectal and parenteral

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Why might you use an oil cosolvent instead of an alcohol

Available for pediatric use, doesn’t evapourate as easily. NB be careful of people’s allergies

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Fixed oil

Non-volatile plant-based oil. Commonly triglycerides of fatty acids from seeds.

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Acidifiers Def

Substances that donate H+ ions to increase acidity (decrease pH) of solution. Alters solubility and permeability of substance. Eg citric acid and HCl

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Alkalizers Def

Substances that donate an OH-, increasing alkaline of solution (increases pH). Alters solubility and permeability. Eg potassium hydroxide and sodium bicarbonate

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Solubilisers Def

Increase apparent solubility of derug. Substance with hydrophilic outer region and drugs dissolves in internal lipophilic regions. Eg cyclodextrin and polysorbates

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Manufacturing and Processing Excipients

Wetting agent, levigating agent, clarifiers, humectants and bulking agents

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Wetting agent Outline

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Hydrophobic powder displaces air and allows it to be wetted by water. Water covers particle and increases contact with air (liquid has to be energetically favourable)

Levigating Agents Outline

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Liquid/ semi-solids used to reduce particle size. Grinding on an ointment slab

Clarifiers Outline

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Filter aids adsorb any undissolved solid particles, subsequently removed by filtration. Leaves a clear solution. Eg crospividone

Humectants Outline

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Lower vapour pressure and just reducing chance of evapouration eg glycol

Bulking Agents Outline

H bonds with protein instaed of water. Prevents the denaturation of proteins. Ensure stability of dosage forms. Eg trhalose

Preservatives Outline

Substance that extend the shelf life of medicines. Preventing oxidation and bacterial growth (bactericidal and bacteriostatic)

Preservative Selection Criteria

No toxicity/irritation/sensitivity, inhibit bacterial growth, broad spectrum, soluble and must be active over wide pH (doesn't need to meet all criteria)

Where do you get info on excipients

Inactive Ingredients Database

Quaternary Ammonium Compounds Outline

Very effective perservative. Positively charged N bound to 4 other elements. Positively charged over all pHs (non proton sensitive). Not for internal use (irritant).

Parabens Def

Structurally similar akyl, esters of p-hydroxybenzoic acids. Greater activity (more permeable) as C chain increases but less soluble. Chelating agents increase activity

Preservatives in sterile dosage forms

Need to autoclave

Methyl Paraben Outline

Active at pH 4-9 (decreasing activity at high pHs), autoclaved in aqueous solutions, may sorb to certain plastics

What is a beneficial property of antimicrobial

Having both antibiotic and antifungal. Minimise amount of excipient required eg Benzoic acid, sorbic acid

Benzoic acid Outline

Only active (absorbed) at low pH (<4), only sparingly soluble in water. Works by intracellular acidification and protein binding making cell membranes leaky

Sorbic acid outline

Optimal between pH 4.5 and 6. Weaker acidifer then benzoic acid. Acts as surfactant due to carboxylic tail. Can be oxidised into toxix biproduct (uncommon).

Preservative Efficacy Testing outline

Challenge complete product (full dosage form) to up to a million bacterial cells. Use log fold reduction to measure efficacy. Shows how well product responds overtime to bacteria (in the 1000s). Test organism example: pseudomonas aeruginosa

Why aren't there preservatives to prevent hydrolysis

Due to water usually existing in excess no substance will ever really be preferentially hydrolysed

Oxidation Outline

Adding O or removing H from compound. Changing drug structure, reducing shelf life. 3 steps: initiation, propogation (chain reaction) and termination

Antioxidant Outline

Reducing agents that are themselves preferentially oxidised in the presence of the drug (preventing drug from being oxidised). They stop process at initiation step of reaction

True Antioxidants Outline

React with free radicals stopping process at propagation eg

Reducing antioxidants Outline

Reducing agents that are preferentially oxidised stopping process at initiation eg sorbic acid

Synergists Outline

Enhance antioxidants eg EDTA

Palatability enhancers

Optimising taste, smell, texture, sight and sound.

Children preferences

Sweet with no undertones (bitter, sour, ect). Have stronger taste receptors

Sour chemical property

acidic

Salty chemical property

cations and anions

Bitter chemical property

High Mw

Sweet chemical properties

polyhydroxyl compounds

Sharp chemical properties

Unsaturation

How to mask tate

Flavour blending (eg acid and lemon), Flavour overshadowing, suspension/emulsion formation, viscosity enhancers (eg carbomer, adsorption/complexation of drug, cooling/heating sensation (tounge irritation) and sialagogue (increased salivation = less time in mouth eg citric acid)

Solution Excipients Flashcards

(50 cards)