Compounding of Pastes – PST05208 Pharmaceutics Theory and Compounding
NTA Level 5 • Semester 2 • PST05208 Compounding of Pastes Pharmaceutics Theory and Compounding • Source Session/Topic 8 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 8 Compounding of Pastes Total Session Time: 120 Minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: Define paste Describe procedures for preparing paste Prepare paste Label prepared paste Dispense prepared paste into suitable containers and closure Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board, chalk and whiteboard markers • LCD projector and computer • Figure 8.1: Paste jars and tube SESSION OVERVIEW Activity/ Step Time Content Method 1 05 Minutes Presentation Introduction, Learning Tasks 2 10 Minutes Presentation Definition of Paste 20 Minutes Presentation Procedures for Preparing Paste 3 Buzzing 45Minutes Presentation 4 Preparing Paste Demonstration 20 Minutes Presentation 5 Labeling of Prepared Paste 10Minutes Presentation Dispensing of Prepared Paste into Suitable Containers 6 Brainstorming and Closure 7 05 Minutes Presentation Key Points 57 8 05 Minutes Presentation Evaluation SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning tasks and clarify ASK students if they have any questions before continuing. STEP 2: Definition of Paste (10 minutes) • Pastes are external semi-solid preparations containing large proportions (20% -60%) of solids finely dispersed in the basis • Pastes are like ointments but contain more solid materials and are stiffer • Pastes are basically ointments into which a high % of insoluble solid has been added • There are two types of paste: o Fatty pastes e.g.: Lassar's paste o Non greasy pastes e g: Bassorin paste • Examples of pastes o Coal tar paste P.CX (astringent, antipruritic) o Compound zinc paste P.CX (astringent) o Zinc and Salicylic acid Paste P.CX (Lassar‟s paste) astringent • Characteristics o Contain more solids than ointments o Are stiffer than ointments o Are less greasy than ointments o Cause less maceration of the skin o Are less occlusive than ointment This is because of high porosity caused by high powder content o Are more absorbent to exudate weeping lesions o Pastes are less penetrating and less macerating and less heating than ointment o Like ointments; paste forms an unbroken relatively water – impermeable film o Unlike ointments; film formed by pastes is opaque, thus can be used as an effective sun block accordingly. 58 STEP 3: Describe Procedures for Preparing Pastes (20 minutes) Activity: Buzzing (10 minutes) Ask students to brainstorm on the following question: • What are procedures for preparing pastes? ALLOW few students to respond? WRITE their responses on the flip chart/ board CLARIFY and SUMMARISE by using the content below • Preparation more less like ointments o e.g. Compound Zinc Paste P.CX (Syn Zinc Paste) o Zinc oxide, finely sifted ……………….. 25.0g o Starch, finely sifted……………………….25.0g o White soft paraffin……………………….50.0g o The powders are triturated with the melted soft paraffin STEP 4: Preparation of Pastes (45 minutes) Activity: Demonstration (45 minutes) DIVIDE students in small manageable groups. PREPARE equipment and materials needed for demonstration POSITION students so that everyone can see and hear REVIEW steps of preparing pastes with students REFER students to the official formula of preparing compound zinc paste PCx In the Tanzania Pharmaceutical Handbook DEMONSTRATE the procedure of preparing ointments according to the instruction under the official formula in the Tanzania Pharmaceutical Handbook (Mitte 50g) ALLOW one student from each group to do a return demonstration and let others comment on it CLARIFY and SUMMARIZE Using the content below INFORM the students that “every student will practice in the skills laboratory under supervision 59 until is competent” • Official formula given for compound zinc paste PCx Zinc oxide, finely sifted………………………………………………………..25.0g Starch, finely sifted……………………………………………………………..25.0g White soft paraffin………………………………………………………………50.0g Mitte 50.0g for Alex Shabani Thus, amount of official formula = 100g Total amount required = 50g Amount of each ingredient (x) =? FACTOR = required amount Official amount = 50gm = 0.5 100gm Then, amount of each ingredient can be obtain as summarised in the table below: Formula Official amount Factor Required amount Zinc oxide, finely 25.0gm 0.5 12.5gm sifted Starch, finely sifted 25.0gm 12.5gm White soft paraffin 50.0gm 25.0gm Method of preparation • Weigh 12.5g of Zinc oxide, finely sifted and 12.5g Starch, finely sifted • Transfer the weighed ( 12.5g) of Zinc oxide, finely sifted and Starch, finely sifted into a mortar • Weigh 25.0g of white soft paraffin • Add to the powders about two or three times their weight of melted white soft paraffin • After each addition trituration should be done for 3 to 5 minutes • Triturate until it is completely uniform • Then transferred to suitable container, label and ready for dispensing to a patient. 60 STEP 5: Labeling of Prepared Paste (20 minutes) • Labeling o As for ointments Activity: Demonstration (10 minutes) DIVIDE students in small manageable groups. PREPARE equipment and materials needed for demonstration POSITION students so that everyone can see and hear REVIEW steps of writing a label REFER students to the important things required to appear on the label. DEMONSTRATE on how to write a good label ALLOW one student from each group to do a return demonstration and let others comment on it CLARIFY and SUMMARIZE by using the content below INFORM the students that “every student will practice in the skills laboratory under supervision until is competent” • Example of labels: For External Use Only ZINC AND SALICYLIC ACID PASTE PCx 100g Spread paste on white lint and place on to the affected area every twenty four hours for five days. The name of the dispenser and the name and address of the dispensing Institution Preparation date Expiry date Keep Out of Reach of Children Keep away from heat 61 STEP 6: Dispensing of Prepared pastes into