DRUG DOSAGE FORMS & DELIVERY SYSTEMS


Ointments

  • Unguents are semisolid preparations for external application of such consistency that they maybe readily applied to the skin with or without inunction (rubbing)
  • Ointments should be of such composition that they soften but not necessarily melt when applied to the body.
Types of Ointments
  1. Medicated
    Examples: Sulfur Ointment, Zinc Oxide Ointment and Compound Resorcinol
  2. Non-medicated
    Examples: White Ointment
The USP and NF Classify Ointment Bases into Four General Groups
  1. Hydrocarbon bases
  2. Absorption bases
  3. Water removable bases
  4. Water soluble bases
1. HYDROCARBON BASES
— Are water-free, and aqueous preparations may only be incorporated into them in small amounts and then with difficulty.

USES: HC are use mainly for their emollient effect and not intended for penetration into the skin. They are difficult to wash off. They do not “dry out” or change noticeably upon aging.

2. ABSORPTION BASES
      2 TYPES
  1. Those that permit the incorporation of agueous solutions resulting in the formation of water-in-oil emulsion. (Anhydrous absorption bases)
  2. Those that are already water-in-oil emulsion (emulsion base) that permits the incorporation of small additional quantities of aqueous solution
3. WATER REMOVABLE BASE
— Are oil-in-water emulsion that are capable of being washed from skin or clothing with water. For this reason, they are frequently referred to as “water-washable” ointment base.
4. WATER SOLUBLE BASE
— Unlike water-removable bases, which contains both water soluble and water insoluble components. Like water-removable bases, however, water soluble bases are water washable and are commonly referred to as “greaseless” because of the absence of any oleaginous materials.

Preparation of Ointment

1. INCORPORATION

The components of the ointment are mixed together by various means until a uniform preparation has been attained.
In small scale or in extemporaneous compounding of the Rx, the pharmacist may use 2 means:

  • Mixing ingredients in a mortar with pestle until smooth ointment produced.
  • Use a spatula and an ointment slab (a large glass or porcelain plate) to rub the ingredients together (spatulation)
Incorporation of Solid

In preparing ointment by spatulation, the pharmacist works the ointment with a stainless steel spatula but if the components react with metal (such as iodine, tannins, mercuric salts) the hard rubber is used

  1. The ointment base is placed on one side of the working surface.
  2. The powdered components (previously reduced into fine powders) are placed on the other side.
  3. Then a portion of the powder is mixed with a portion of the base until uniform.
  4. Repeat until all portions of the product and based are combine.
  5. The portions of prepared ointment are then combined and thorough blended by continuous movement of the spatula.
Incorporation of Liquids

Liquid substances or solutions of drugs are added to an ointment only after due consideration of the ointment nature.

An aqueous solution would be added with difficulty to the oleaginous ointment, except in very small amount. However, water absorbable hydrophilic ointment bases would be quite suitable for the absorption and incorporation of the aqueous solution.

In case of hydrophobic base and an aqueous solution is to be added, a portion of the hydrophobic base is replaced by a hydrophilic base.

2. FUSION METHOD

By this method, all or some of the components of an ointment are combined by melting together and cooled with constant stirring until congeal.

Those components not melted are generally added to the congealing mixture as it is cooled and stirred.

The heat labile substances and volatile constituents are added last when temperature is low enough not to cause decomposition.


Packaging and Storage for Ointments

Semisolid pharmaceuticals frequently either in jars or in tubes. The jars may be made of glass, uncolored, colored green, amber or blue or opaque and porcelain white. Plastic jars are used in limited extent. The tubes are made of tin or plastic. These are called “collapsible tube”.


Test Requirements for Ointments

  1. Microbial Content
    Meet acceptable standard for microbial test requirements
    Must contain antimicrobial preservatives.

    Preservatives:
    – methylparaben,propyl paraben, phenols, benzoic acid, sorbic,quaternary ammonium salts

    Example: Betamethasone Valerate Ointment — must be absence of Staphylococcus aureus and Pseudomonas aeriginosa

  2. Minimum Fill Test
    — net weight and volume
  3. Packaging, Storage, and Labeling
    — metal, plastic tubes, jar
    Well close containers, light sensitive, light resistant
    Labeling - type of base used (water soluble or insoluble)
  4. Additional Standards
    Examine the viscosity
    Vitro drug release to ensure within lot and lot-to-lot uniformity
Tubes May Be Filled By The Following Steps
  1. The prepared ointment is rolled into a cylinder shape of a piece of parchment paper, the diameter is smaller than that of the tube.
  2. With cap of the tube off to permit escape of air, the cylinder of ointment with the paper is inserted into the open bottom of the tube.
  3. The piece of paper covering the ointments is grasped in one hand, the other hand forces a heavy spatula down on the extreme end of the tube, collapsing it and retaining the ointment while the paper is slowly pulled from the tube. About one half (1/2) inch of the bottom is then flattened with the spatula.
  4. About 1/8 folds are made from the flattened end of the tube and sealed by pliers or sealing clip on foot operated “crimper” machine.
Note: Ointments made by fusion may be poured directly into the tubes. Stored at temperatures below 30°C to prevent softening.