pharmaceutical solutions for oral administration

Pharmaceutical solutions

for oral administration

By :Dr. Nehal Aly Afifi Professor of Pharmacology

Cairo university

Liquid dosage forms

One of the oldest dosage forms used in treatment.

Rapid & High absorption of soluble medicinal products .

Particular use for individuals having difficulty in swallowing SDF

(e.g.: Pediatric, Geriatric, Intensive care & Psychiatric) Patients.

Solutions are homogeneous liquid preparation containing one or

more completely dissolved components (One-phase system).

Active ingredients dissolved within vehicles to obtain uniform sols.

In general, water used as vehicle in w medicaments dissolved,

water is Non-toxic, Nonirritant, Tasteless, Relatively cheap,

and many drugs are water soluble (Aqueous sol.)

Some drugs not water soluble so mixed with other solvents NonAqueous

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Prof.Dr/ Nehal Afifi

Solutions: Definition

Pharmaceutical solutions are extensively used as dosage forms for

the oral administration of therapeutic agents.

Pharmaceutical solutions defined as liquid preparations in which the

therapeutic agent and the various excipients are dissolved in the

chosen solvent system.

Pharmaceutical solutions are homogeneous, i.e. the therapeutic

agent(s) and excipients are dissolved in the vehicle.

Pharmaceutical solutions for oral administration are in non-sterile

dosage forms.

Pharmaceutical sol. classified according to their intended use as

Oral solution, - Otic solution

Ophthalmic solution, - Topical solution.

Parenteral preparations

Sol. categorized by a traditional name related to the solvent system

used and/or their intended function (e.g. Spirits, Syrups Tinctures,

Aromatic waters, and Elixirs).

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• Pharmaceutical solutions contain a range of excipients, each

with a defined pharmaceutical purpose. Examples include:

• The vehicle, usually purified water

• Co-solvents, e.g. propylene glycol, glycerin, alcohol

• Surface-active agents specifically to enhance solubility of

the therapeutic agent in the vehicle.

• Preservatives, e.g. parahydroxybenzoate esters

(methylhydroxybenzoate and propylhydroxybenzoate),

boric acid and borate salts, sorbic acid and sorbate salts.

• Sweeteners, e.g. glucose, saccharin, aspartame

• Rheology (viscosity) modifiers, e.g. hydrophilic polymers

• (cellulose derivatives, alginic acid, polyvinylpyrrolidone)

• Antioxidants, e.g. sodium formaldehyde sulphoxylate,

• butylated hydroxyanisole, butylated hydroxytoluene

• Buffers to regulate the pH of the formulation, e.g. citrate buffer.

Advantages of pharmaceutical solutions

1. The drug immediately available for absorption.

By providing drug in a solution, the dissolution phase

absorption can bypassed → quicker absorption.

2. Flexible dosing is possible. The active ingredient within

sol. present in a certain Conc. per unit volume.

3. Solutions are designed for any route of absorption: the

oral route of administration , via Parenteral preparations

(injections), enemas for rectal use, Topical (for use on

skin) & ophthalmic preparations are all sols.

4. No need to shake the container. Unlike suspensions

as the active ingredient is dissolved within the vehicle.

5. Facilitate swallowing in difficult cases (e.g. infants or

the elderly). It is more easier for patients to take solution

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Disadvantages of solutions

1. Drug stability is reduced in Sol by hydrolysis or oxidation.

For this reason, Sol. is commonly has a shorter expiry date

than equivalent solid dosage forms.

2. It is difficult to mask unpleasant tastes.

3. A major disadvantage ; they are much larger & more bulky,

difficult to transport.

Liquids packed in glass bottles are obviously prone to breakage

and cause loss of the preparation.

4. Technical accuracy is needed to measure the dose on admin.

patient accuracy in measuring a dose is required

5. Some drugs are poorly soluble so it is necessary to alter

vehicle or drug form in order to formulate a convenient prep.

6. A measuring device is needed for admin. so need to be

supplied to the patient to be able to measure an accurate dose

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Advantages & disadvantages of pharmaceutical

solutions for oral administration

Advantages Disadvantages

• 1. Drug available immediately

for absorption→ bioavailability

of sols is greater than that

of oral solid-dosage forms.

• 2. Flexible dosing.

• 3. designed for any route of

administration.

• 4. Not need to shake

container.

• 5. Facilitates swallowing in

difficult cases.

1.Drug stability reduced in sol.

• 2. Difficult to mask unpleasant

tastes.

• 3. Bulky, difficult to transport

& prone to container

breakages.

• 4. Technical accuracy needed

• to measure dose on administ.

• 5. Measuring device needed

for administration.

• 6. Some drugs poorly soluble

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Formulation of Pharmaceutical sol.

Drug(s) + Range of excipients include:

The vehicle ( Solvent):

- Purified Water.

- Oil

• Co-solvents, e.g. propylene glycol , glycerol, ethanol

surface-active agents

- To enhance solubility of the therapeutic sub. in vehicle.

Preservatives,

- Against microbial contamination

Sweetening agents, e.g. glucose, saccharin, aspartame

Viscosity modifiers, e.g. cellulose derivatives,

Antioxidants, e.g. butylated hydroxytoluene

Coloring & Flavoring agents (oral only)

Buffering agents , to regulate the pH of the formulation,

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Drug Solubility

• In pharmaceutical sols both therapeutic drugs and the

excipients are required to be present in sol over the shelf-life.

• As a result solutions are termed homogeneous.

• 1.IF the aqueous solubility of drug is high at the selected pH of

formulation, → therapeutic drug is readily incorporated into

vehicle and formulated as oral sol.

• 2.IF aqueous solubility of drug is moderate at selected pH , i.e.

aqueous solubility is less than requested conc. of drug→ the

solubility of drug in sol. must be enhanced using co-solvents.

• 3.IF aqueous solubility of drug is low at selected pH of

formulation. The difference between aqueous solubility of drug

and the required conc. is too great to the use of cosolvents or

surfactants in the solubilised form & toxic when administered

orally. The drug therefore formulated as a suspension

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Factors Affecting Solubility

• 1- physicochemical properties of Therapeutic agent :

• The solubility of drug molecules in a solvent are dependent on

several physicochemical properties, including molecular weight,

volume, density, and number of hydrogen bonds.

• Particle size:

• Reduction of particle size increase the rate of solubility.

• The solubility of a chemically related series of drugs is

inversely related to their melting points; so as the melting

point of drug increased, the solubility decrease.

• The solubility of a drug is directly affected by the type of

chemical substituent groups.

• The solubility of drugs containing hydrophilic groups (e.g.

OH, COO, ammonium ion) will accordingly be greater than

those containing lipophilic substituent groups, e.g.

methyl, ethyl, or chlorine groups.


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• 2- Temperature:

• Most compounds are more soluble in higher temperature.

• 3- pH

• The vast majority of drug subs. are either acids or bases .

• The solubility of therapeutic agents are pH-dependent.

• The solubility of acids & bases increases as the degree of

ionization increases.

• The solubility of acidic compounds increases as the pH

of the sol. is increased (above the pKa) & solubility of

basic comps increase as the pH is lowered below the pKa

4. Polarity:

Polar comp. more soluble in Polar solvents as water & ethanol .

Non polar comps more soluble in non polar solvents as chloroform

Conc. acid or alkali added to form water- soluble salts.

Conversilly,The organic bases more soluble in organic

solvents than the corresponding salt forms.

Methods to enhance/optimize the solubility

1. Appropriate selection of drug salt:

• The majority of therapeutic agents are available in a salt

form, each form a different aqueous solubility.

• Select the drug salt provide the required solubility in

the dosage form.

• 2. Optimization of the pH of the formulation:

• The solubility of ionized therapeutic agent is a function of both

the pKa and the pH of the formulation.

• The acceptable pH range for oral sols is large, ranging from 5 to

8 pH units.

• The selection of a pH value for formulation to optimize the

ionization and solubility of the therapeutic agent is important.

• The Control of pH in formulation is achieved by using a buffer


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3. Use of co-solvents :

Co-solvents are liquid components incorporated into a

formulation to enhance the solubility of poorly soluble drugs.

The Commonly employed co solvents include , glycerol,

propylene glycol, ethanol and polyethylene glycol.

The final choice of the co-solvent system for a particular

formulation involves consideration of the solubility of the

therapeutic agent in the vehicle, the toxicity of the vehicle

and the cost of formulation.

The range of concentrations of each co-solvent used in oral

formulations is primarily limited by concerns regarding

toxicity.

Excipients used in pharmaceutical solutions

for oral administration

• Excipients are pharmacologlly inert compounds that are

included in the pharmaceutical formulations.

• To facilitate the administration of the dosage form, e.g.

pourability, and palatability,

• To protect the formulation from issues regarding physical

and chemical stability.

• To enhance the solubility of the therapeutic agent.

• Pharmaceutical sols contain a wide range of excipients.

• l- The vehicle:

• The preferred & most commonly used vehicle in sols for

oral administration is Purified Water USP, due to the low

cost and low toxicity .


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Vehicles (Solvents) for Liquid Dosage Forms

A vehicle is the medium containing the ingredients of a drug.

In solutions, the vehicle is the solvent.

The choice of a vehicle depends on:

The intended use of the preparation

The nature & physicochemical properties of active ingredients.

Water as a vehicle

Water used as the primary solvent; widely available,

relatively inexpensive, palatable and non-toxic for oral

use, non-irritant for external use.

Water is also a good solvent for many ionizable drugs.

Salts of organic compounds are more soluble in water

water is the preferred solvent. for solutions to be taken orally,

used ophthalmic ally, or injected.

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Types of water 1. Potable water : drinking water, should be palatable &

safe for drinking, Its chemical composition may include

mineral impurities which could react with drugs, e.g. the

presence of calcium carbonate in hard water.

2. Purified water USP, obtained from potable water by

distillation, ion exchange treatment,or reverse osmosis.

Distilled water is purified water prepared by distillation.

Compared with ordinary drinking water:

Purified Water, more free of solid impurities.

When evaporated to dryness, not yield greater than

0.001% of residue (1 mg of total solids /100 mL of sample

evaporated).

Purified Water is intended for use in preparation of

aqueous DF, except those intended for Parenteral

administration (injections).

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Water as a vehicle

3. Water for preparations : potable or freshly boiled and cooled

water, used in oral or external LDF not intended to be sterile.

4. Water for injections: is pyrogen-free distilled water, sterilized

immediately after collection and used for Parenteral

preparations.

5. Chloroform water : used as antimicrobial preservative and

also adds sweetness to preparations. chloroform available as:

Chloroform BP = 100% v/v

6. Aromatic water : saturated solution of volatile oils in water

and are used to provide a pleasant flavor or aroma, e.g.

Peppermint Water, USP.

Used as a vehicle in oral sol. Some have mild carminative action

For example diluted Aromatic waters are usually prepared from

a conc. ethanolic sol. in a dilution of 1 part to 39 parts with water.

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• II. Co-solvents

• Employed to increase the solubility of therapeutic agent

within the formulation.

• Co-solvents used in the formulation of oral solutions are :

• Glycerol (also termed glycerin)

• Glycerol is a clear odorless, viscous liquid, with a sweet taste

, and miscible with both water and alcohol.

• Its co-solvency properties due to the presence of three

hydroxyl gps;oH. It has similar co-solvency properties to ethanol

• Alcohol USP (CH3CH2OH)

• Contain between 94.9 and 96.0% v/v ethyl alcohol(ethanol).

• Commonly used as a co-solvent, both as a single and with

other co-solvents, e.g. glycerol.

• The known pharmacological & toxicological effects of alcohol

have compromised its use in pharmaceutical preparations.


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• Propylene Glycol USP

• Propylene Glycol is an odourless, colourless, viscous liquid

that contains two hydroxyl groups; oH .

• Used in pharmaceutical preparations as a co-solvent,

generally as a replacement for glycerin.

• III. Miscellaneous agents used to enhance solubility of

• therapeutic agents.

• These include the use of surface-active agents & Complexation.

• A. Surface-active agents

• These are chemicals that possess both hydrophilic (water-liking)

and hydrophobic (water-disliking) regions.

• At dilute conc. surface-active agents will orient at the interface

between two phases (e.g. water/oil), with the hydrophilic and

hydrophobic regions of the molecule being positioned to the

hydrophilic and hydrophobic phases, respectively.

Surface-active agents

• As the conc. increased, the interface will become saturated with

surface-active agent & the molecules that are present in the

bulk aqueous phase will orient themselves to shield the

hydrophobic regions of surface-active agent.

• This orientation is referred to as a micelle المذيلة.

• The conc. of surface-active agent at this occurs is termed the

critical micelle concentration (CMC).

• In this the core of the micelle represents a hydrophobic

region into which the poorly water-soluble drugs partition.

• For example, if the therapeutic agent is poorly soluble, the

molecule will locate exclusively within the micelle.

• if the drug is water-insoluble but contains polar groups, the

molecule will orient within the micelle, w & drug solubilised

within the colloidal micelles; due to their small size →the

resulting sol. appears homogeneous to the naked eye.


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B. Complexation

• Complexation refers to the interaction of a poorly

soluble therapeutic agent with an organic molecule,

e.g. surface-active agents, hydrophilic polymers to

generate a soluble intermolecular complex.

• One particular concern regarding the use of solution of

drug complexes is the ability of the complex to dissociate

following administration.

• This is particularly important in situations where the

complexing agent is a hydrophilic polymer, as the

high molecular weight of the drug–polymer complex

would prevent drug absorption across biological

membranes.


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IV. Common Excipients in Pharmaceutical Sol.

• Excipients that are commonly employed in formulation of

pharmaceutical solutions are: (1) buffers; (2) sweetening

agents; & (3) viscosity-enhancing agents.

• (1) Buffers:

• Buffers employed within pharmaceutical sols to control pH of

the formulated product and, to optimize the physicochemical

performance of the product.

• Typically pH control is performed:

To maintain the solubility of therapeutic agent in formulated prod

• The solubility of drugs is pH-dependent , therefore, solubility

of therapeutic agent compromised by small changes in pH

To enhance the stability of the products in which the

chemical stability of the active agent is pH-dependent.


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• The conc. of buffer salts employed in the oral solutions

should be selected to offer sufficient control of the pH of the

formulation but yet should be overcome by biological fluids

following administration.

• Examples of buffer salts used in pharmaceutical solutions

include:

• ■ Acetates (acetic acid and sodium acetate): about 1–2%

• ■ Citrates (citric acid and sodium citrate): about 1–5%

• ■ Phosphates (sodium phosphate and disodium

phosphate): about 0.8–2%.

• the buffer system used in solution formulations should not

adversely affect the solubility of the therapeutic agent, e.g.

the solubility of drugs may be affected in the presence of

phosphate salts.

Sweetening Agents

• Sweetening agents are employed in liquid formulations

designed for oral administration specifically to increase

the palatability of the therapeutic agent.

• The main sweetening agents employed in oral

preparations are sucrose, liquid glucose, glycerol,

sorbitol, saccharin sodium and aspartame.

• The use of artificial sweetening agents in formulations

is increasing and, in many formulations, saccharin

sodium is used either as the sole sweetening agent or in

• combination with sugars or sorbitol to reduce the sugar

• concentration in the formulation.

• The use of sugars in oral formulations for children and

patients with diabetes mellitus is to be avoided.


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Viscosity -enhancing Agents

• The administration of oral solutions to patients by using a

syringe, a small-metered cup or a traditional 5-ml spoon.

• The viscosity of formulation must be controlled to ensure the

accurate measurement of the dispensed volume.

• increasing the viscosity of → increase the palatability.

• Certain liquid formulations do not require the addition of VEA,

e.g. syrups, due to their inherent viscosity.

• The viscosity of pharmaceutical solutions increased by the

addition of non-ionic or ionic hydrophilic polymers.

1. Non-ionic (neutral) polymers: – cellulose derivatives e.g.:

● methylcellulose ●hydroxyethylcellulose

• ● hydroxypropylcellulose

• –– Polyvinylpyrrolidone

2. Ionic polymers: – sodium carboxymethylcellulose (anionic)

• – sodium alginate (anionic).


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Antioxidants • Antioxidants included in pharm. Sol. to enhance the stability of

drugs that susceptible to chemical degradation by oxidation.

• Antioxidants are compounds that inhibit free radical-induced

drug decomposition.

• Both water-soluble & water-insoluble antioxidants are available.

• Antioxidants for aqueous formulationse eg; Sodium sulphite,

sod. metabisulphite, sod. formaldehyde sulphoxylate and

ascorbic acid.

• Antioxidants used in oil-based solutions e.g; butylated

hydroxytoluene (BHT), butylated hydroxyanisole (BHA) and

propyl gallate.

• Antioxidants employed in low concentrations ( ˂ 0.2% w/w) .

• Antioxidants employed in conjunction with chelating agents,

e.g. ethylenediamine tetraacetic acid, that act to form

complexes with heavy-metal ions.


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Preservatives

• Preservatives are included in pharmaceutical solutions to

reduce or prevent the microbial growth of the formulation.

• Ideally, preservatives should exhibit the following properties:

• 1. possess a broad spectrum of antimicrobial activity

includes Gram-positive,Gram-negative bacteria & fungi.

• 2.be chemically and physically stable over the shelf-life

of the product. 3. have low toxicity.

• Preservatives for use in oral pharmaceutical solutions :

• ■ benzoic acid and salts (0.1–0.3%).

• ■ sorbic acid and its salts (0.05–0.2%).

• ■ Alkyl esters of parahydroxybenzoic acid (0.001-0.2%).

• A combination of two preservatives employed in solutions

to enhance the antimicrobial spectrum.

• Methyl & propyl parahydroxybenzoates (in a ratio 9:1).

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Flavours and colourants

• The vast majority of drugs in solution are unpalatable,→ so

the addition of flavors to mask the taste of drug subs.

• Flavours added to make a medicine more acceptable to take.

• Four basic taste sensations are salty, sweet, bitter & sour

• – Flavours used to mask a salty taste include:

● butterscotch ● apricot ● peach ● vanilla● wintergreen mint.

• – Flavours used to mask a bitter taste include:

● cherry. ● mint. ● anise.

• – Flavours used to mask a sweet taste include:

● vanilla. ● fruit and berry.

• – Flavours used to mask a sour taste include:

● citrus flavours. ● raspberry.

• A combination of flavours is used to achieve the optimal

taste-masking property.

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Flavour Adjuncts

• Certain excipients added to oral solution formulations, referred

to as flavour adjuncts (e.g. menthol, chloroform).

• flavour adjuncts add flavor to formulation and in addition, act to

desensitise the taste receptors.

• These agents augment the taste-masking properties .

• Colourants:

• Colours are pharmaceutical ingredients that impart the preferred

colour to the formulation.

• When used in combination with flavours, the selected colour

should ‘match’ the flavour of the formulation,

• e.g. green with mint-flavoured solutions,

• red for strawberry-flavoured formulations.

• Although colours is not a prerequisite for all pharmaceutical sol.,

certain categories of solution (e.g. mouthwashes/gargles) are

normally coloured.


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Types of pharmaceutical solutions

• Pharmaceutical sols for oral administration:

• 3 principal types of sol. formulations administered

orally: oral solutions, oral syrups and oral elixirs.

• Other sol. formulations employed for a local effect, e.g.

• mouthwashes/gargles .

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Oral solutions

• Oral solutions are administered to the GIT to provide systemic

absorption of the therapeutic agent.

• Oral solutions formulated over a broad pH range due to the

flexibility of GI environment.

• The usual pH of oral solutions is about 7.0, unless there are

issues regarding the solubility or stability of drug.

• Typically the following excipients used in the formulation:.

• ■ Buffers (e.g. citrate, phosphate)

• ■ Preservatives (e.g. parabens, benzoic acid, sorbic acid).

• ■ Antioxidants (water-soluble antioxidants used, e.g.

sodium metabisulphite 0.01–1.0% w/w)

• ■ Flavours and colours.

• ■ Viscosity-modifying agents (to affect the pourability of the

Formulation, hydrophilic polymers are used, e.g. sodium

alginate, hydroxyethylcellulose).


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Oral syrups

• Syrups are highly concentrated, aqueous sols of sugar or a

sugar substitute that contain a flavouring agent, e.g.

• cherry syrup, orange syrup, raspberry syrup.

• Unflavored (Traditional syrup) composed of aqueous sol.

containing 85% sucrose.

• It is important to ensure that:

• 1.The drug substance soluble within the syrup base.

• 2. The syrup vehicle is appropriate to physicochemical

properties of drug subs. For example, cherry syrup &

orange syrup are acidic, therefore solubility of acidic drugs

lowered & resulting in precipitation of drug subs.

• The use of acidic syrups additionally result in reduced

chemical stability for acid-labile therapeutic agents.


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• The major components of syrups are as follows:

• ■ Purified water

• ■ Sugar (sucrose) or sugar substitutes(Artificial sweeteners.

• ■ Preservatives. ■ Flavours. ■ Colours.

• Traditionally syrups composed of sucrose (60 and 80%) and

purified water. [Not need the addition of other sweetening agents

,viscosity-modifying agents , or preservatives].

• Sorbitol is a non-sucrose bases replace traditional syrup In some

formulations.

• Sorbitol Sol. USP contains 64% w/w sorbitol (a polyhydric alcohol)

• Other alternatives based on mixtures of sorbitol & glycerin available

• Non-sucrose bases mixed with traditional syrups, if the oral syrups

possess a low conc. of sucrose.

• More recently, many products formulated as medicated sugar-free

syrups due to the glycogenetic & cariogenic properties of sucrose.

Medicated Sugar-free Syrup

• All Medicinal products designed for

administration to children & diabetic

patients must be sugar-free.

• Syrup Substitutes must provide an

equivalent sweetness, viscosity and

preservation to the original syrup.

• Artificial sweeteners:

• Artificial sweeteners include Saccharin sodium, and Aspartame.

• Non-glycogenetic viscosity modifiers (e.g.methylcellulose, and

hydroxy ethyl cellulose) .

• Preservatives(e.g. sodium benzoate, benzoic acid &parahydroxy

benzoate ester ) are included in medicated sugar-free syrup.


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therapeutic agent

Saccharine Sod.

purified water

Preservative

flavoring agents

Preservatives

• Preservatives are not required in traditional syrups containing

high conc. of sucrose.

• Addition of preservatives is required in: 1. sugar-free syrups,

2. syrups in which sucrose substituted by polyhydric alcohol.

3. traditional syrups contain lower conc. of sucrose,

• Examples of commonly used preservatives include:

• Mixtures of parahydroxybenzoate esters (methylhydroxy

benzoate and propylhydroxybenzoate in a ratio of 9:1).

• The typical concentration range is 0.1–0.2% w/v.

• The preservative efficacy decreased in the presence of

hydrophilic polymers (generally employed to enhance

• viscosity), due to interaction of preservative with polymer.

• Other preservatives include benzoic acid (0.1–0.2%) or

sodium benzoate (0.1–0.2%).


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Flavours

• Flavours employed to the unpalatable taste of a therapeutic agent

even in presence of the sweetening agents.

• The conc. of flavour in oral syrups is that which required to

provide the required degree of taste-masking effectively.

• 1.The flavours of natural origin (e.g. peppermint, lemon, herbs )

and available as oils, extracts, spirits or aqueous sol.

• 2. synthetic flavours:

• Certain flavors also associated with a (mild) therapeutic activity,

e.g; antacids contain mint due to the carminative effect.

• flavours offer a taste-masking effect by eliciting a mild local anesthetic

effect on the taste receptors,e.g;peppermint oil, chloroform, menthol.

• ■ Colours :natural or synthetic water soluble, photo-stable

ingredients that selected according to flavour of preparation.

• E.g;, mint-flavoured formulations with a green colour, banana-

flavoured sol. with a yellow colour . Must not chemically or

physically interact with the other components of the formulation.


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Oral elixirs

• Elixir is a clear, hydroalcoholic sol. formulated for oral use.

• The presence of alcohol in elixirs cause a problem in paediatric

formulations and, for adults who wish to avoid alcohol.

• The typical components of an elixir are as follows:

• ■ Purified water.

• ■ Alcohol: employed as a co-solvent to ensure solubility of all

ingredients. the conc. Of alcohol varies depending on formulation.

• Generally, Alcohol conc. is greater than 10% v/v; however, in

some preparations, alcohol conc. greater than 40% v/v.

• ■ Polyol co-solvents. e.g. propylene glycol, glycerol, employed

in elixirs to enhance the solubility of drug subs. & excipients.

• The inclusion of co-solvents enable the alcohol conc. to be

reduced. The conc. of co-solvents is dependent on conc. of

alcohol present;e.g; in USP: Phenobarbital Elixir & Theophylline

Elixir


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• 1. Phenobarbital Elixir: • Phenobarbital (therapeutic agent) 0.4% w/v

• Orange oil (flavour) 0.025% v/v

• Propylene glycol (co-solvent) 10% v/v

• Alcohol 20% v/v

• Sorbitol solution (sweetener) 60% v/v

• Colour As required

• Purified water ad 100%

• 2. Theophylline Elixir • Theophylline (therapeutic agent) 0.53% w/v

• Citric acid (pH regulation) 1.0% w/v

• Liquid glucose (sweetening agent) 4.4% w/v

• Syrup (sweetening agent) 13.2% v/v

• Saccharin sodium (sweetening agent) 0.5% w/v

• Glycerin (co-solvent) 5.0% v/v

• Sorbitol solution (co-solvent) 32.4% v/v

• Alcohol 20% v/v

• Lemon oil (flavour) 0.01% w/v

• FDC yellow no. 5 (colour) 0.01% w/v

Linctuses

• A liquid oral preparation used for a demulcent,

expectorant or sedative effect in treatment of cough.

• Linctuses are viscous preparations that contain the

therapeutic agent dissolved in a vehicle composed of a

high percentage of sucrose and, if required, other

sweetening agents.

• These formulations are administered orally.

• Primarily employed for treatment of cough, due to their

soothing actions on the inflamed mucous membranes.

• Linctuses also be formulated as sugar-free alternatives

in which sucrose is replaced by sorbitol and the required

Conc. of sweetening agent.


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Mouthwashes /gargles

• Mouth washes/gargles are designed for the treatment of

infections and inflammation of the oral cavity.

• Formulations designed for this purpose employ water as

the vehicle, although a co-solvent, e.g. alcohol, may be

employed to solubilise the active agent.

• The use of alcohol as a co-solvent act to enhance the

antimicrobial properties of the therapeutic agent.

• Other formulation components are frequently required to

enhance the palatability and acceptability of preparation.

• These include preservatives, colours, flavouring agents

and non-cariogenic sweetening agents.

• Oral drops: oral solutions or suspensions administered in

small volumes, using a suitable measuring device.

• E.g.; Abidec® vitamin drops.


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Solutions for oral dosage

• Containers for dispensed oral solutions:

• Plain, amber medicine bottles should be used, with a re-closable

child-resistant closure.

• A 5 mL measuring spoon or an appropriate oral syringe should be

supplied to the patient.

• Advice to store away from children should then be given. Special labels and advice for dispensed oral solutions:

• An expiry date should appear on the label for the final prepared

sols. Most 'official' mixtures & some oral sols are freshly prepared.

• 'Official' elixirs, linctuses and manufactured products are generally

more stable, unless diluted.

• Diluted products generally have a shorter shelf life than undiluted

preparation.

• Linctuses should sipped & swallowed slowly without addition of water

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pharmaceutical solutions for oral administration

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