The project developed sodium silicate ointment with a view to achieving both topical and systemic release through co-solvency preparation technique. The effects of two ointment bases: she butter and petrolatum in the presence of propylene glycol, and menthol in the release of sodium silicate was studied.
Release studies of the two ointment bases were. Characteristic physical and reorganization tests were performed on both formulations, including melting temperature, pH, net weight uniformity, and membrane permeability. Texture, appearance and spread was checked. The texture was a bit gritty, significantly mint, appearance was yellowish for she based, and white for petrolatum based, both batches spread significantly well, and were noticeably difficult to was off with water. The formulations using petrolatum were generally more by volunteer test subjects, compared to the she butter based formulation.
The melting temperature was uniform across batches. Petrolatum formulations melted at close to body temperature, 38 degrees while the she based had an average melting point of 36. 5 degrees Celsius. The pHs on formulation of the she based formulations were Alkaline, ranging from 7. 39-7. 95. While petrolatum based formulations were only slightly alkaline (6. 95-7. 12). All formulations noticeable increased in alkalinity on storage. The net weights ranged from 69-71 g across batches. Consistency tests showed a range of 190-21 Mom and 203-mm for and she butter respectively.
They also carry medicament for persecutors and further action on deeper layers of tissue. Some are targeted to release medicament to the blood stream. (Remington et al, 1975). Ointment therefore could be defined as soft, semisolid preparation intended, for application to the skin or coetaneous tissue. (Fouled et al, 2002). An Ointment can also be defined as viscous semisolid preparation used topically on a variety of the body surfaces. These include the skin and the mucus membrane of the eye (an eye ointment) vagina, anus, and nose. (Netscape online, 2002).
An ointment may or may not be medicated. The application could be with or without rubbing. It consists of a base which acts as a carrier for the medicament. The type of base used in its formulation is very important since it influences its performance; therefore the selection of suitable ointment base is a very important parameter in every ointment preparation. Such a base should be relatively inexpensive, non-irritating, easiest removable, non-staining, non-pH dependent, stable and fairly compatible with a wide variety of medicament. (Fouled et al 2002). There have been a number of studies on the role of topical vehicles in precautions absorption of drugs. Majority of workers have thought that the function of the medicament and the absorbing cell. However resent studies have revealed that they lay more complex roles. Oleaginous based have been found to release drug poorly due to their low water absorbing capacity on the other hand, ointments of the emulsion or water soluble type tend to release medicament much more rapidly and completely probably due to their water miscible nature (Stratton and Clark, 1943).
It is obvious that a continuous water phase would be miscible with secretions of wounded and oozing surfaces of abraded skin. By so doing, the release of medicament is enhanced. Diffusion of drug through the base has been observed to the limiting factor in drug release, (Highchair 1963). Most often therefore, Ointment bases are classified based on their composition. They could also be classified on the bases of their therapeutic action based on their degree of penetration on application to the skin. (Fouled et al 2002). However the classification below is based on their definite composition and properties. ) Hydrocarbon bases (oleaginous) 2) Water-removable bases (Emulsion base W/O type) 3) Absorption bases (Anhydrous) 4) Water soluble bases (Emulsion IOW type) 1. 2. 1 the properties of the ointment bases Hydrocarbon bases Greasy, Emollient, Hydrophobic Occlusive, Non water-washable. . Absorption bases Greasy, Emollient, Anhydrous, Occlusive, Absorb water. 3. Water-removal bases classified as a) Emulsion (o/w) type b) Emulsion (o/w) type Greasy, Emollient contain water occlusive, some absorb additional water. Non- greasy, can be diluted with water, non-occlusive water washable. 4.
Water-soluble and washable Non-greasy, lipid free, usually anhydrous non-occlusive, water soluble and washable. Some Examples of Ointment Bases and their Classification Petrolatum (white & yellow) paraffin, plastic base (delude), microelectronics wax. 2. Hydrophilic petrolatum Water-removable bases ) Emulsion NV’ type Emulsion W/O type Hydrophilic ointment 4. Water-soluble bases Polyethylene glycol ointment (Fouled et al 2002) Some Factors that may Affect the Choice of an Ointment Base Include: I) Stability it) Penetrability iii) Solvent property iv) Irritant effects v) Ease of application and removal 1. . 2 Some Additives Used in Ointments To maintain the potency and integrity of ointment and to protect the health and safety of the consumer a number of additives are added to the ointment beside the base and the medicament. Some of these additives are stated and explained below. I) Preservatives The presence of microorganisms in non-sterile products like ointments pose a potential hazard, therefore carefully selected antimicrobial preservatives are added to prevent contamination, deterioration of ointment bases by bacteria and Fungi.
An ideal preservative suitable for this function should possess the following properties. A) Non toxic and non sensitivity b) Compatible with ingredients of the base on the package components c) Inexpensive d) Stable and free from foul odors and colors it) Antioxidant It may be necessary to select suitable antioxidant whenever there is possibility of oxidative degradation of the base. Ii) Chelating Agent Suitable compatible and selected chelating agents are being added to ointment bases when there are possibilities of traces of metallic ions likely to influence oxidative degradation of citric and phosphoric acid. V) Perfumes This imparts a pleasant odor to the ointment base its addition is most often by choice. There are two basic methods in ointment formulation. They include: a) Mechanical incorporation method b) Fusion method Mechanical Incorporation This is a technique where the active ingredient is incorporated into the ointment ease using simple spatula and ointment slab. Adequate precaution should be taken where there is danger of chemical reaction between the spatula and certain medicament e. G. Tannic acid, salicylic acid, etc.
When a liquid is to be incorporated into an ointment base, pestle and mortar is often used. Fusion Method This method is normally adopted when hard and waxy ingredients such as PEG, paraffin, soft materials like petrolatum, surfactants, glycols and water are involved. In in a water bath, and other materials of lower melting points are subsequently added in order of their decreasing melting point. Adequate skill must be applied to ensure that separation of the fused ingredients is prevented. Volatile oils and perfumes and added after the base has cooled to about ICC to ICC.
Whichever method adopted, there are four guidelines that the formulator must keep in mind and they include: 1 . The finished product should be free from granular particles, gritty feels and be thoroughly homogeneous. 2. Drugs that are soluble in water may be dissolved in small amount of water before incorporation in the base. 3. Insoluble solids should always be in the impalpable powder form and should be levitated with a small reaction of the base prior to incorporation with the remainder of the base. 4. Drugs that are soluble in the ointment base may be incorporated by fusion.
The higher melting ingredients of base should be melted first and medicament mixed up. Thereafter other ingredients can be mixed up with stirring (Fouled et al, 2002).Ointments are generally subjected to the following tests. I. Penetration Test This involves rubbing a weighed quantity of the ointment over a definite area of the skin for a given length of time. The unabsorbed ointment is collected from the skin ND weighed. The difference between the two weights represents the amount absorbed or at least gives an idea of the amount of the amount of the ointment absorbed. T. Measurement of Rate of Release of Medicament Here, the agar diffusion method is employed to assess the rate of release of an incorporated drug from an ointment. Small quantity of the ointment is placed on the surface of a nutrient agar contained in a Petri dish. If the incorporated drug is an antimicrobial agent, the agar is first seeded with suitable susceptible organisms. After incubation the inhibition zone is measured. Alternatively, the ointment is smeared on the internal surface of the test tube. The test tube is filled with Saline (0. 9% NCAA) or serum.
After some time, the amount of drug in the saline or serum is estimated using appropriate assay technique. Results obtained give an idea in the rate of drug release from the ointment. Anther method involves putting a portion of the ointment in a Jar. The Jar closed with cellophane and suspended in water. The amount of incorporated drug diffusing into the water is determined with appropriate assay methods. Iii. Adsorption of Medicament into Blood Stream Here, a definite amount of ointment is rubbed on the skin and the incorporated drug which is absorbed into the systemic circulation is estimated in blood plasma or in the urine. Iv.