Compounding Corner January 2019

31.01.2019

Compounding of Oral and Topical Powders (January 2019)

Powder is a dry preparation of medicinal or chemical ingredients, for oral use or for external use. Oral powders are preparations suitable for children and adults who find it difficult to swallow capsules or tablets. Powders have a large surface area that is more soluble and dispersed than other solid dosage forms. Powder formulations are homogeneous, dry, with uniformity of content. Topical powder must be free of Clostridium Tetani, Clostridium Welchii, and Bacillus Anthracis bacteria.

 

Powder classification

1.      Oral Powder

Oral powder can either be in a divided or an undivided form.

Oral divided powder is, powder that is packaged and intended as a single dose. Whereas, for oral undivided powder it can be given as multiplel doses over several time interval. such as; laxative, antacids e.t.c (the condition of undivided powder is that the drug is relatively non-potent to avoid dosing errors).

2.      Topical Powder

Topical powder is a powder intended for external use. For examples, Dusting powders, Tooth powders.

 

The principle of powder mixing

Powder mixing can be used to maintain powder homogeneity and the availability of active ingredients in the powder so that there is no active ingredient attached to the mortar wall.

1. Potential drugs are mixed with fillers

2. Drugs in the form of crystals, before mixing must be crushed

3. Drugs that have different colors, must be mixed until they are homogeneous

4. Medicines that have a small volume or amount must be mixed first, then drugs with a larger volume or amount

 

Steps in preparing powders

1. Particle size reduction.

This aims to enlarge the surface area, so that the powder can be more easily dissolved and dispersed. while, Topical powders do not cause irritation to the skin after use. The degree of fineness of a powders is expressed as the percentage of powder that passes the sieve size that meets the specifications.

Here is the degree of fineness of a powders according to BP 2013

Degree of fineness

Not less than 95% by mass passes through a number

Not more than 40% by mass passes through a number

Coarse powder

1400 sieve

355 sieve.

Moderately fine powder

355 sieve

180 sieve

Fine powder

180  sieve

125 sieve

Very fine powder

125 sieve

90 sieve

Reducing particle size can be done in two main ways:

a. Trituration.

Is a process of reducing particle size using mortars and pestle. Trituration is used when working with hard and fracturable powders.

b. Pulverization by Intervention

Pulverization by intervention is used with hard crystalline powders that do not crush or triturate easily, gummy type substances. In pulverization by intervention, we use solvent (such as alcohol or acetone) that will dissolve the compound, and then mixed in a mortar, and evaporation of the solvent Is then carried out.

 

2. Mixing of powders. This aims to form homogeneous and evenly mixed powder preparations. Homogeneity of the preparation is very important because it is related to the uniformity of content and effectiveness of treatment. Some powder mixing methods are as follows.

a. Trituration

It is  a mixing process using a mortars and pestle. This method is commonly used by pharmacists.

b.  Geometric dilution.

The active ingredient (potent drug) is placed in a mortar, then added to an approximately same amount of the fillers / diluent. This  is mixed quickly by trituration. After being homogeneous, the mixture is added to another approximately same amount of filler and mixed again by trituration. The process continues until all the fillers is added.

c. Spatulation

It is a method of mixing powder using a spatula on a piece of paper. This can be used for mixing solid ingredients that can liquefy or form eutectic mixtures.

d. Tumbling by mechanical mixing

It is a mixing method using tools with large rotating container such as powder blenders, V-blend, etc. This method is usually done in industry for mixing on a large scale.

 

3. Packaging of powders

a. Oral powders

Oral divided powders can be wrapped in parchment paper or other types of paper and then put into a card-box or plastic. The packaging of oral undivided powders can use plastic pots or large-mouthed jars that make it easy to take.

b. Topical powders

Topical powders especially dusting powders can be packed in  containers with holes such as sieves or in large-mouthed containers.

 

References

  • Allen, L. V., Popovich, N. G., Ansel, H. C., & Ansel, H. C. (2005). Ansel's pharmaceutical dosage forms and drug delivery systems. Philadelphia: Lippincott Williams & Wilkins.
  • British Pharmacopoiea Commision. (2013). British Pharmacopoiea. London: The. Pharmaceutical Press.
  • Christopher A Langley, Dawn Belcher. (2012) FASTtrack: Pharmaceutical Compounding and Dispensing. London: Pharmaceutical Press.
  • Marriott J F, Wilson K A, Langley C A, Belcher D (2006) Pharmaceutical Compounding and Dispensing. London: Pharmaceutical Press.

Example cases

Prescription:

Date.

05 January 2019

Patient’s

Information

Name

John

Doctor’s Name

Ken

Date of birth / Age

05 July 1997 / 21 years

Doctor’s Signature

Ken

Calamine Dusting Powders 15% BP 200 g

Direction

Apply the dosage to the affected areas two times a day

 

1. Compound Name:

2. Content of the compounded medicine in active pharmaceutical ingredient:

3. Pharmaceutical form:                                                         

4. Quantity of the compounded medicine:

5. Route of administration :

6. Beyond-Use Date:

7. Formulation

Ingredient

Quantity

Organoleptic

Function

 

 

 

 

 

 

 

 

 8. Calculations for the amounts of prescribed drugs

Ingredient

Quantity

Quantity Calculated

 

 

 

 

 

 

  9. Method of preparation

 

 

10. Compound label

Patient:                                              Manufacturing Date: ________________

Drug:                                                  Strength (% w/w):

Indication:

Directions:

Storage:

Pharmacist name:                             Amount:

 


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