Speaking. Complete the sentences.

8) The principles modes of extraction …..

9) The process of maceration ….

10) The physical forces…..

11) The instrument used ….

12) But the powdering of the drug ….

Writing. Complete the sentences using the following words:

Pharmacy, a percolator, the cells, the drug, the menstruum, the mase, strengths.

1) The drugs are macerated in definite quantities of…..

2) The menstruum consists of alcohol of various …..

3) Percolation is one of the most important methods of drug extraction employed in …..

4) The instrument used to hold the powder is called ….

5) The soluble principles of vegetable substances are generally contained in ….

6) The process of maceration consists simply of extraction by soaking ….

7) The residual drug remaining in the percolator after the extraction of the soluble constituents is called …

Writing. Fill in the table.

Noun

Verb

Adjective

Adverb

Extraction, introduce, useful, simply, soluble, solution, extract, various, partially, substance, rapid, cellular, highly, proportion, coloured, separate, powder, granulated, apply.

Writing. Open the brackets choosing the necessary form of the participle.

1) For the determination of vitamin B1 the (testing, tested) solution was diluted with water.

2) The instrument (using, used) to hold the powder is called a percolator.

3) The (preparing, prepared) suppository forms were placed in a refrigerator for 3 days.

4) When (subjecting, subjected) to a low temperature and high pressure carbon dioxide is converted into a liquid.

5) The physical forces (played, playing) an important part in the percolation are gravitation, viscosity, surface tension.

6) The time (requiring, required) for 90% drug release was 15 min. for tablets (making, made) with tragacanth.

Speaking. Answer the following questions.

1) What principle modes of drug extraction are used in pharmacy?

2) What is the most important and useful method of drug extraction?

3) What process is called maceration?

4) What are the drugs macerated in?

5) What does the menstruum consist of?

6) In what process is a granulated or powdered drug deprived of its constituents?

7) In what process do physical forces play an important part?

8) What instrument is called a percolator?

9) What proportion of the percolate is usually the most dense?

10) What would the process of percolation be if the soluble principles could be separated from the insoluble cellular substance and be deposited in the ground particle?

Writing. Fill in the table.

Drug extraction

The principle modes

The physical forces

Speaking. Make up a dialogue on the theme “Drug extraction”.

Writing. Write an annotation to the “Drug extraction”.

Work-out for practical study

Theme: «Ointments. Preparation of ointments»

Pre-reading task. Speaking.

8) What do you know about ointments?

9) What do you know about preparation of ointments?

List of new words

Ointment base absorption base

efficiency wide-mouth jard

penetration contamination

possess incorporation

lard fusion

levigating trituration

oleaginoses stirring

excessive oil-miscible substance

Reading

Ointments

Ointments are semi-solid preparations for external application of such consistency that they may be readily applied to the body or to mucous membranes.

They should be of such composition that they soften but not necessarily melt when applied to the body.

The ointment base usually constitutes the major portion of the pharmaceutical preparation and therefore, may influence the efficacy of the incorporated medical substances.

Based on their penetration ointments have been divided into three classes. Epidermic ointments are those which demonstrate no, or very slight, power of penetration into the skin. In this group have been placed the bases which contain petrolatum, waxes and their combinations.

Endodermic ointments are those which possess some power of penetration into the deeper layers of the skin. Most of them have a somewhat lower melting point, approaching the temperature of the skin, and contain vegetable oils, lard, wool fat, lanolin, and/or combinations of these.

Diadermic ointments are those which penetrate the skin, thus offering a better opportunity for absorption of the medicament. Ointments of emulsion type and the water-soluble bases belong to the group of absorption base.

Preparation of ointments

Ointments are prepared by two methods: 1) mechanical incorporation and 2) fusion. The choice of method depends upon the medicament and the physical properties of the constituents of the base. An exception is the preparation of Mercuric Nitrate Oinment which is prepared by chemical reaction.

Preparation by Incorporation. Mechanical incorporation performed by trituration in water, or a glass slab with a spatula, is more frequently used by the pharmacist than any other method. The medicaments being incorporated into a base are frequently insoluble in the base and it is necessary, therefore, to reduce them to an impalpable powder. Best results can be obtained by using a small portion of the base and gradually incorporating the powder.

It is very advantageous to use a small amount (approximately 5 per cent) of an oil or an oil-miscible substance as a levigating agent when preparing oleaginous ointments.

Certain medical substances, such as the pilular extracts of vegetables drugs or agents which are soluble in a certain solvent, are more easily distributed through the base by first softening with such solvents. Some salts such as potassium iodide, the alkaloidal salts and others may be dissolved in water provided they are very soluble. Some substances such as menthol can be dissolved in a small amount of liquid petrolatum prior to incorporation.

Preparation by Fusion. When wax, spermaceti, resin, or other hand, fusible bodies are to be incorporated with soft, oleaginous materials they are melted on a water bath to avoid excessive temperatures, beginning with the material possessing the higher fusion point and adding the other ingredients in order of decreasing values until the softer oleaginous and perhaps liquid ingredients, have all been thoroughly incorporated by stirring. The medication in fine powder is then slowly sifted into the melted materials. If large quantities of aqueous liquids are to be incorporated with melted oleaginous materials, as in the preparation of Rose Oinment, the liquid should be warmed and them added slowly with constant stirring or trituration to the mixture.