Powders in Pharmaceutics-2023-24
Powders
Definition— A pharmaceutical powder is a mixture of finely divided drug and or chemicals in powder form. These are solid dosage form of medicament which are meant for internal and external use. They are available in crystalline or amorphous form.
Chemical properties, biological properties and therapeutic efficacy depends on the particle size of the powder, because dissolution rate and absorption rate vary as per the different particle size.
Classification of the powders.
- Unit dosages powder— Cachets, simple powder, compound powder, tablet triturates, effervescent powder.
- Bulk dosages powder.
- Bulk powder of external use— Dusting powders, insufflation, dentifrice, snuffs.
- Bulk powder of internal use— fine powder, antacid and laxative powder.
Advantages of powders.
- These are the oldest dosage form used both internally and externally.
- These are more stable than liquid dosage form.
- It is convenient for the physician to prescribe a specific amount of powdered medicament depending upon the need of the patient.
- Due to the smaller particle size its dissolution rate is very high and it show the high therapeutic effects.
- The large quantity of drug can be administered easily by dissolving the powdered in an appropriate liquid.
Disadvantages of powder.
- Drugs having bitter, nauseous and unpleasant taste cannot be dispensed in powdered form.
- Deliquescent and hygroscopic drugs can’t be dispensed in powder form.
- Drugs which get affected by atmospheric conditions are not suitable for dispensing in powder forms.
- The dispensing of power is a time consuming.
- Quantity less than 100mg or so cannot be weight conveniently or dispensing balance.
- Powder form is not suitable for drugs that are inactivated or cause damage to the stomach.
Granules.
Definitions— Granules are basically aggregation of fine particles of the powders in a mass of about spherical shape.
Classification of granules.
- Effervescent granules.
- Coated granules.
- Gastro-resistant granules.
- Modified release granules.
Advantages of granules.
- They have good flowability than powders
- They also remove or control the dust.
- They increase the compressibility.
- Their physical and chemical stability is much more than powders because they have a smaller surface area.
- They give rise to particle size uniformity, which further leads to content uniformity.
Insufflations.
Definition— Insufflations are a class of powders meant for application into body cavities E.g., Ear, nose, vagina etc. The powder has to be extremely fine and must find an entry to the cavity deep enough to bring about its action the site.
It is delivered to the effected part in a stream with the help of the device called an insufflator, which blow the powder to the site. Pharmaceutical industry packages the insufflations in pressurized from. Example- Aerosols.
- Aerosols contain the medication in a stout container with a suitable valve the delivery of the powder being accomplished by a liquefied or compressed gas propellant of a very low boiling points. On pressing the actuator of the valve, the propellant delivers the medication in a stream.
Dusting powders.
Definition— Dusting powders are externally used bulk powders. They are free flowing very fine powders containing antiseptic, antipruritic, astringents, antiperspirants, absorbents lubricants etc. They provide protection to the skin against irritation caused by friction moisture or chemical irritations. It mainly contains antimicrobial agent like chlorhexidine and hexachlorophene.
- Medicated dusting powder—Medicated dusting powder usually contain substance such as zinc oxide, starch and boric acid or natural mineral substances, such as kaolin or talc. Talc may be contaminated with pathogenic micro-organisms such as clostridium tetani, etc. and hence it should be sterilized by dry heat.
- It is meant for the superficial skin, to reducing the infection, fungal growth, temporarily absorb the moisture and provide the smooth feel and cooling effect.
- Surgical dusting powder—Surgical dusting powders are intended to be used into deep layer of skin and also on major wounds as a result on burns and umbilical cords of infants. It must be free from pathogenic entity. Example-Neosporin dusting powder.
Effervescent powders.
Definition—Effervescent powders create a carbonated drink when added to room temperature water. For evolution of carbonated gas two constituents are essential, a soluble carbonate such as sodium bicarbonate and an organic acid such as citric or tartaric acid. Example: Eno, etc.
This class of preparations can be supplied either by compounding the ingredients as granules or dispensed in the form of salts. This dosage form is useful for patients who do not tolerate capsules/tablets, who need a high dose of the active ingredient and who need are more palatable flavour for the drug.
The combination of the carbonation and the flavour (i.e., mango, passion fruit or raspberry) can override the negative taste of the active ingredient.
Effervescent granules.
Definition— Granular solid dosage form consisting of one or more active medicament in a dry mixture usually composed of sodium bicarbonate, citric acid and tartaric acid when added to water the acid and base react to liberate carbon dioxide resulting in effervescences and are administered as carbonated solutions. Active medicaments ex: Antacids, Laxatives, Antibiotics, Antipyretics etc.
The effervescent granules (salts) are prescribed to the dispensed in bulk form. The ingredients are mixed uniformly and directions stated on the label to add the prescribed quantity to water before use.
Differences between powders and granules.
Powders | Granules |
It is fine particles | Granule is small grain |
It applies on the both externally and internally | Granule generally used for internally |
Powder is smooth to the touch | Granules are rough |
Relatively poor flow properties | more than powder |
Physically and chemically less stable | Physically and chemically more stable |
Produce more dust | Produce more dust |
D.Pharma Notes
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