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Article
Pharmacy Times
How can I extemporaneously compound a vehicle for transdermal delivery of progesterone
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Various vehicles are employed by pharmacists who compound preparations for transdermal delivery of active ingredients. United States Pharmacopoeia?grade active ingredients?such as progesterone, testosterone, and various estrogens?are available for the preparation of ?bioidentical? hormone formulations.
One method involves the use of a gel that exhibits inverse temperature-viscosity behavior: it becomes more viscous as it is warmed, providing a sticky mass when applied to the skin. Sometimes referred to as Polox (a trademark for reconstituted 20% and 30% aqueous gel with preservatives), it is made from the gel basis Pluronic F127NF with preservative.
Pluronic F127NF is a trade name for a particular Poloxamer resin. Poloxamers are specified in the NF (monograph products) as excipients. As noted, the gel is a liquid at refrigerated temperatures and becomes more viscous upon warming: storage in a refrigerator will make compounding with it easier. To this gel is added a penetration enhancer to make PLO, a commonly used pharmacy name for Pluronic Lecithin Organogel, which consists of Poloxamer (Pluronic) gel with added lecithin and isopropyl palmitate or isopropyl myristate.
One lecithin?isopropyl palmitate system is known commercially as Lipoil and is a 50:50 (w/w) eutectic mixture of solid lecithin and liquid isopropyl palmitate (liquid and solid, respectively, at room temperature). It is a liquid at room temperature but may become solid on cooling. It is stored at room temperature and is thawed in a water bath if received in a solid condition.
When applied to skin under occlusive dressing (such as Tegaderm or OpSite), the system provides a thick gel with penetration enhancers. PLO has a tan and ?creamy? appearance. It is not a clear ?gel? per se, but it is a pharmaceutical gel. One might be hard pressed to discern the difference between this base and a ?cream.? A pharmacist, however, will quickly note a distinct difference in texture, mobility, and the like.
A convenient method for preparation of the gel is given in the following general formulation for compounding a PLO gel?based product. This formulation is calculated to make 100 mL.
Ingredients
Active ingredient
XX.XXX mL
Suitable solvent
XX.XXX mL
Lipoil
24.000 mL
Polox 20% gel
qs ad 100.000 mL
Supplies
Balance with weights and weigh boats Graduated cylinder
Mortar and pestle or 60-mL and 140-mL syringes with Luer lock to Luer lock connector Oral syringes and caps and Luer lock to oral slip connector
Procedure
Mortar and Pestle Method
Syringe Method
Notes
Ingredients
Progesterone micronized
3.600 g
Suitable solvent (eg,
ethyl alcohol 200 pf,
propylene glycol)
3.600 mL
Lipoil
28.800 mL
Polox 20% gel qs ad 120.000 mL
Procedure as above
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