The final prices may differ from the prices shown due to specifics of VAT rules About this book This book provides a list of concise extemporaneous ophthalmic preparations, and standardizes the formulation of the products by suggesting specific strength, route of administration, appropriate vehicle, and method of preparation. Pharmaceutical industries have greatly expanded their share of ophthalmic drugs in recent years. However, physicians and pharmacists are frequently called to prepare sterile products intended for ophthalmic use due to lack of availability of licensed drugs in the market. This book contains the most appropriate formulation of each medication based on published and documented stability data. Extemporaneous Ophthalmic Preparations is the first book of its kind, making it a unique and valuable companion for many physicians and pharmacy practitioners who are frequently engaged in the compounding of sterile ophthalmic preparation. Eman A.
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It is bacteriostatic and fungistatic at neutral and alkaline pHs, but bactericidal at acidic pH levels. Although it is stable at room temperature, it is also light sensitive. In other words, antioxidants stabilize the drug. Common antioxidants include ethylenediaminetetraacetic acid more commonly known as edetate disodium [EDTA] , sodium metabisulfite, and sodium bisulfite.
Sodium metabisulfite is useful in acidic solutions, whereas sodium bisulfite is used in neutral pH solutions. Viscosity increases drug absorption and therapeutic effects. The viscosity of ophthalmic solutions ranges from 25 centipoise cps to 50 cps. Viscosity agents must usually be sterilized by autoclaving before addition to an ophthalmic preparation because they cannot be sterilized through filtration.
Commonly used viscosity agents include hydroxyethylcellulose, hydroxypropyl methylcellulose HPMC or hypromellose, methylcellulose, polyvinyl alcohol PVA , and polyvinyl pyrrolidione or povidone.
HPMC is preferred over methylcellulose because it produces solutions with greater clarity and has soothing and lubricating properties. However, the eye tolerates tonicity ranging from 0.
From a practical viewpoint, patients generally tolerate hypertonic solutions very well. Only vehicles and lubricating solutions, such as artificial tears, must be isotonic. Common tonicity agents include dextrose, glycerin, and sodium chloride. Filtering solutions through a 0. Using HPMC can serve a dual purpose in ophthalmic preparations.
Polysorbates, e. For example, most drugs are acidic or neutral and will precipitate, rendering the drugs inactive if added to a basic solution or vehicle. A precipitate in an ophthalmic preparation could also potentially cause an corneal abrasion. As mentioned previously, thimerosal is bacteriostatic in neutral or basic pHs, but bactericidal in acidic pHs.
Buffers are used in ophthalmics when the pH is critical and must be within a certain range. Ideally the buffer capacity should be less than 0. Ophthalmic buffering agents are usually citrate, phosphate, or acetate buffers. Depending on the dosage form and indication, the vehicle or base may contain lubricants, wetting agents or demulcents, electrolytes, viscosity agents, or buffering systems. There are basically 2 types of vehicles and bases: aqueous and oleaginous or nonaqueous.
It is very common to use commercial balanced salt solutions or artificial tears as a vehicle for topical solutions; however, different brands differ in content and may not be interchangeable.
For example, if a stability study indicates it used the Systane brand of artificial tears, compounders cannot substitute another brand, like Murine Tears, and assign the BUD established in the study. Systane contains polyethylene glycol and propylene glycol, whereas Murine Tears contains polyvinyl alcohol and povidone.
These brands are not equivalent or interchangeable even though they are both artificial tear solutions. These solutions may also be used to prepare topical solutions. Nonsterile ointment bases can only be sterilized by dry heat.
Autoclaves sterilize by a combination of heat and pressure to create steam. Since an ointment contains no water, no steam is generated to sterilize it. Bland lubricating ophthalmic ointments that do not have active ingredients consist of 3 basic ingredients in various concentrations: white petrolatum, mineral oil, and lanolin. Yellow petrolatum is not used in ophthalmic preparations because it is less purified than the white petrolatum and can be more irritating to the patient.
For topical "oily" solutions, some fixed oils, such as corn oil or medium chain triglycerides oil, are also safe to use and can be sterilized by filtration through a 0. Active pharmaceutical ingredients APIs may be obtained from commercial sterile products, such as parenterals, nonsterile bulk powders, or liquids. Most compounded ophthalmics can be prepared with commercial sterile products; however, some compounders may need to prepare them using non-sterile components, which requires sterilizing processes and may require extensive end-preparation testing depending on the BUD and volume produced.
They are not considered emergent, life-threatening treatments, however, and should be prepared in a controlled, sterile environment. However, some compounded ophthalmic dosage forms are prepared from bulk APIs because of manufacturer backorders or the compounded medication is not commercially available. They may be prepared as a single unit for an individual patient, or prepared as a batch in multiple units for an individual patient or multiple patients.
Compounders should read, understand, and implement this chapter of the United States Pharmacopeia before preparing compounded sterile medications. Mathematical calculations used to develop the formula should be double-checked to minimize error. For example, use a 3 mL syringe to measure a 2. The 5 mL syringe has 0. Compounders must inspect all ophthalmic dosage forms visually for clarity and particulate matter.
Suspensions must be easily suspended when shaken, with no caking on the bottom. Ointments must be smooth, not grainy. The color must be as expected for that particular formulation. Finally, the compounder should check the pH to ensure that the solution is within a range suitable for the active ingredient s and the eye itself. This is a minimum standard.
Certain ophthalmic preparations can be easily contaminated and support fungal growth. Typically, endotoxins are known for causing fever and other complications when injected into the bloodstream. Potency testing should be done initially with the development of a new formula to ensure that the concentration of active medication and the process to prepare the dosage form is accurate.
For preservative-free preparations, it would be prudent to package the preparation in single-dose sterile bottles or syringes. Properly preparing compounded ophthalmic dosage forms is essential in providing good quality preparations to effectively treat a delicate organ, the eye. Ophthalmic Drugs—Diagnostic and Therapeutic Uses. London, UK: Elsevier; Eye Health Topics.
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Extemporaneous ophthalmic preparations
Extemporaneous Ophthalmic Preparations