SOLUTIONS Dosage forms prepared by dissolving

the active ingredients in an aqueous or non aqueous solvent.

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

Solutions can be formulated for different routes of administration:

Orally - Syrups, elixirs, drops

In mouth and throat - Mouthwashes, gargles, throat sprays

In body cavities - Douches, enemas, ear drops, nasal sprays

On body surfaces: Collodions, lotions

Advantages

Easier to swallow

More quickly effective than tablets and capsules

Homogenous therefore give uniform dose than suspension or emulsion which need shaking

Dilute irritant action of some drugs (Aspirin, Kl, KBr)

Minimize adverse effects in the GIT like KCl.

Disadvantages

Bulky therefore difficult to transport and store.

Unpleasant taste or odors are difficult to mask.

Needs an accurate spoon to measure the dose.

Less stable than solid dosage forms. Major signs of instability: color change, precipitation, microbial growth, chemical gas formation

Additives

BUFFERS Used to resist any change in pH.

VISCOSITY ENHANCEMENT It is difficult for aqueous-based topical

solutions to remain on the skin or in the eye therefore low concentrations of jelling agents are added to increase the viscosity of the product

PRESERVATIVES prevent the growth of microorganisms.

Also used to preserve the product.

Alcohols

Ethanol is useful as a preservative when it is used as a solvent. It needs a relatively high concentration (greater than 10%) to be effective.

Propylene glycol also used as a solvent in oral solutions and topical preparations. It can function as a preservative in the range of 15 to 30%. It is not volatile like ethanol.

Acids Benzoic acid and sorbic acid have low

solubility in water. They are used in a concentration range from 0.1 % to 0.5%. Only the non-ionized form is effective and therefore its use is restricted to preparations with a pH below 4.5.

ANTIOXIDANTSUsed to suppress oxidation of the product. Oxidation reaction is initiated by heat, light and heavy metals. Antioxidants as propyl & octyl esters of gallic acid, tocopherols or vitamin E, sodium sulfite, ascorbic acid (vit. C) can be used.

SWEETENING AGENT Sucrose is the most widely used sweetening agent.

Polyhydric alcohols (sorbitol, mannitol and glycerol) possess sweetening power and can be used for diabetic preparations.

FLAVORS AND PERFUMESIt mask the unpleasant taste or odor and enable the easy identification of the product.Natural products: fruit juices, aromatic oil (peppermint, lemon, cinnamon)Artificial perfumes are cheaper, more readily available and more stable than natural products.

Classification of Solutions According to Vehicle

Aqueous solutions Non-aqueous solutions

Aqueous Solutions

Aqueous solutions are homogeneous mixtures that are prepared by dissolving a solid, liquid or gas in an aqueous medium (vehicle).

Vehicle: This may be water, aromatic water or extracts.

Methods of Preparation of Solutions

Simple SolutionsSolutions of this type are prepared by dissolving the solute in a suitable solvent (by stirring or heating). The solvent may contain other ingredients which stabilize or dissolve the active ingredient.

Solution by Extraction Plant or animal products are prepared by suitable extraction process. Preparations of this type may be classified as solutions but more often, are classified as extractives.

Solution by Chemical ReactionThese solutions are prepared by reacting two or more solutes with each other in a suitable solvent e.g. Calcium carbonate and lactic acid used to prepare Calcium lactate mixture.

Pharmaceutical Solutions

Aqueous Sweet or Viscid Non-Aqueous1. Douches 1. Syrups 1. Elixirs

2. Enemas 2. Honeys 2. Spirits3. Gargles 3. Collodions4. Mouthwash 4. Glycerin5. Nasal wash 5. Liniments6. Juices 6. Oleo Vitamin7. Sprays8. Otic Sol’n9. Inhalations

Aqueous Aqueous SolutionSolution

Douches

Douche is an aqueous solution, which is directed against a part or into a cavity of the body.

It functions as a cleansing or antiseptic agent. Eye douches are used to remove foreign particles and

discharges from the eyes. It is directed gently at an oblique angle and is allowed to run from the inner to the outer corner of the eye.

Pharyngeal douches are used to prepare the interior of the throat for an operation and to cleanse it in supportive conditions.

Similarly, there are nasal and vaginal douches. Douches most frequently dispensed in the form of a

powder with directions for dissolving in a specified quantity of water.

Enemas

These preparations are rectal injections employed to evacuate the bowel (evacuation enemas)

Retention enemas are used in small quantities (about 30ml) and are thus called retention microenema.

Starch enema may be used either by itself or as a vehicle for other forms of medication

Gargles

Gargles are aqueous solutions frequently containing antiseptics, antibiotics and/or anesthetics used for treating the pharynx (throat) and nasopharynx by forcing air from the lungs through the gargle, which is held in the throat; subsequently, the gargle is expectorated.

Many gargles must be diluted with water prior to use. Although mouthwashes are considered as a separate class of pharmaceuticals, many are used as gargles, either as is, or diluted with water.

The product should be labeled so that it cannot be mistaken for preparations intended for internal administration.

Mouthwashes

Mouthwashes can be used for therapeutic & cosmetic purposes Therapeutic mouthwashes can be

formulated to reduce plaque, gingivitis, dental caries and stomatitis.

Cosmetic mouthwashes may be formulated to reduce bad breath through the use of antimicrobial and/or flavoring agents.

Mouthwashes are used as a dosage form for a number of specific problems in the oral cavity

Nasal Solutions

Nasal solutions are usually aqueous solutions designed to be administered to the nasal passages in drops or sprays. Ephedrine Sulfate or Naphaxoline Hydrochloride

Nasal Solution USP are administered for their local effect to reduce nasal congestion

Lypressin Nasal Solution USP for its systemic effect for the treatment of diabetes insipidus

Commercial nasal preparations include antibiotics, antihistamines and drugs for asthma prophylaxis.

Nasal decongestant solutions are employed in the treatment of rhinitis of the common cold and for allergic rhinitis (hay fever) and for sinusitis.

Sprays

Sprays are solutions of drugs in aqueous vehicles and are applied to the mucous membrane of the nose and throat by means of an atomizer nebulizer.

The spray device should produce relatively coarse droplets if the action of the drug is to be restricted to the upper respiratory tract. Fine droplets tend to penetrate further into the respiratory tract than is desirable.

Otic Solutions

The main classes of drugs used for topical administration to the ear include local anesthetics (benzocaine),antibiotics (neomycin), and anti-inflammatory (cortisone) agents.

These preparations include the main types of solvents used, namely glycerin or water.

The viscous glycerin vehicle permits the drug to remain in the ear for a long time.

Anhydrous glycerin, being hygroscopic, tends to remove moisture from surrounding tissues, thus reducing swelling.

Viscous liquids like glycerin or propylene glycol either are used alone or in combination with a surfactant to aid in the removal of cerumen (ear wax).

SWEET OR VISCID SOLUTIONS

Syrups are concentrated solutions of sugar such as sucrose in water

or other aqueous liquid. Simple syrup: when water is used alone for making syrup. Medicated syrup: when the aqueous preparation contains

some added medicinal substance Flavored syrup: which contains aromatic or pleasantly

flavored substances and is intended to be used as a vehicle or flavor for prescriptions

Honeys Are thick liquid preparations. At one time, before sugar

was available, honey was used as a base, instead of syrup. There are few official preparations containing honey. e.g.

Oxymel, or “acid honey” is a mixture of acetic acid, water and honey.

NON-AQUEOUS SOLUTIONS

Elixirs

Are clear, pleasantly flavored, sweetened hydroalcoholic liquids intended for oral use.

They are used as flavors and vehicles e.g. Dexamethasone Elixir USP and Phenobarbital Elixir USP.

The main ingredients in elixirs are ethanol and water but glycerin, sorbitol, propylene glycol, flavoring agents, preservatives, and syrups are often used in the preparation of the final product.

EIixirs contain ethyl alcohol, however, the alcoholic content will vary greatly, from elixir containing only a small quantity to those that contain a considerable portion as a necessary aid to solubility

An elixir may contain water and alcohol soluble ingredients.

Spirits

Alcoholic or hydroalcoholic solutions of volatile substances. The active ingredient may be gas, liquid or solid.

Spirits may be used internally for their medicinal value, by inhalation but is mostly used as flavouring agents.

Spirits should be stored in tight, light-resistant containers and in a cool place

Spirits are preparation of high alcoholic strength and when diluted with aqueous solutions or liquids of low alcoholic content turbidity may occur

Colloidons

Are liquid preparations containing pyroxylin (a nitrocellulose) in a mixture of ethyl ether and ethanol.

They are applied to the skin by means of a soft brush or other suitable applicator and, when the ether and ethanol have evaporated, leave a film of pyroxylin on the surface.

The official medicated collodion, Salicylic Acid Collodion USP, contains 10 % w/v of Salicylic Acid in Flexible Collodion USP and is used as a keratolytic agent in the treatment of corns and warts.

Collodion is made flexible by the addition of castor oil and camphor.

Glycerins

Glycerins or glycerites are solutions or mixtures of medicinal substances in not less than 50% by weight of glycerin.

Most of the glycerins are extremely viscous. Glycerin is a valuable pharmaceutical solvent

forming permanent and concentrated solutions not otherwise obtainable.

Glycerin is used as the sole solvent for the preparation of Antipyrine and Benzocaine Otic Solution USP. As noted under Otic Solutions, glycerin alone is used to aid in the removal of cerumen.

Glycerins are hygroscopic and should be: stored in tightly closed containers.

Liniments

Are solutions or mixtures of various substances in oil, alcoholic solutions of soaps, or emulsions.

They are intended for external application and should be so labeled.

They are applied with rubbing to the affected area, the oil or soap base providing for ease of application and massage.

Alcoholic liniments are used generally for their rubefaciant and counterirritant effects. Such liniments penetrate the skin more readily than do those with an oil base.

The oily liniments are milder in their action and may function solely as protective coatings.

Liniments should not be applied to skin that are bruised or broken.

Oleo Vitamins

Oleo vitamins are fish liver oils diluted with edible vegetable oil or solutions of the indicated vitamins (usually vitamins A and D).

The indicated vitamins are unstable in the presence of rancid oils and, therefore, those preparations, should be stored in small, tight containers, preferably under vacuum or under an atmosphere of an inert gas, protected from light.

Calcium Hydroxide

Calcium Hydroxide is a white powder having alkaline and bitter taste.

It is slightly soluble in water, glycerin,syrup and very soluble in boiling water.

Insoluble in alcohol When exposed in air, it reacts with

Carbon Dioxide and produces Calcium Carbonate which is insoluble.

Calcium Hydroxide Solution

Clear, colorless liquid having an alkaline taste and is alkaline to litmus.

Prepared by adding 3g of Ca(OH)2 to 1000 ml of Purified water.

Mixture is agitated repeatedly for 1 hr and excess Ca(OH)2 is allowed to settle. The clear, supernatant liquid is used.

It is used medicinally as fluid electryolyte and as topical astringent.

CALCIUM HYDROXIDE SOLUTION

SSynonym: Slaked Lime, Calcium HydrateLLatin Name: Calcium Hydroxide solutionUUse of the Preparation: Used medicinally as fluid electrolyte and

as topical astringent. Ingredient Quantity Physical

DescriptionUse in

Formula

Calcium Hydroxide

0.3 g Fine, white powder

Active Ingredient

Purified Water 100 ml Clear, colorless liquid

Solvent

Appropiate container for the preparation: Tight Container

Description of finished product: Clear, supernatant liquid

Recommended storage conditions: Preserve in well-filled, tight containers, at a temperature not exceeding 25 C

Labelling Information:Calcium Hydroxide SolutionCalcium Hydroxide...............................0.3gPurified Water......................................100mlStore with temperature not below 25 C.

1. What are the different processes/methods of preparing solution? Describe each method.

Simple Solution - Solutions of this type are prepared by dissolving the solute in a suitable solvent by stirring or heating.

Solution by Chemical Reaction -These solutions are prepared by reacting two or more solutes with each other in a suitable solvent.

Solution by Extraction - Plant or animal products are prepared by suitable extraction process. Preparations of this type may be classified as solutions but more often, are classified as extractives.

2. Can the undissolved portion of the mixture of Ca(OH)2 solution still be used? Why?

No, because it is not suitable for preparing additional quantities of Ca(OH)2 solution.

3. What is the chemical reaction of Ca(OH)2 upon exposure to the air? What is the insoluble carbonate formed?

Ca(OH)2 + CO2 → CaCO3 + H2O

The insoluble carbonate is CaCO3.