SAF Emulsions and Creams_1.PDF

SAINS FORMULASI EXTEMPORANEOUS PREPARATION: EMULSION AND CREAMS (PART 1) PM Dr. Ng Shiow Fern FAKULTI FARMASI  Disperse Systems Interface Continuous phase Disperse phase  Disperse Systems Name Dispersed phase Di...

SAINS FORMULASI EXTEMPORANEOUS PREPARATION: EMULSION AND CREAMS (PART 1) PM Dr. Ng Shiow Fern FAKULTI FARMASI  Disperse Systems Interface Continuous phase Disperse phase  Disperse Systems Name Dispersed phase Dispersion medium Examples Solid suspension Solid Solid Pigmented Plastics Solid emulsion Liquid Solid Ointment Solid foam Gas Solid Expanded polystyrene Sol, suspension Solid Liquid Aluminium hydroxide suspension Emulsion Liquid Liquid Creams, lotion Foam Gas Liquid Foam on surfactant solution Solid Aerosol Solid Gas Smoke, powder aerosol Liquid Aerosol Liquid Gas Fogs, mists, aerosols 3  Pharmaceutical Emulsions Oral Always o/w 2 types: nutritional oil/supplement (e.g. fish liver oil, soya bean oil) and local effect (constipation liq paraffin) Don’t have to be sterilised Emulsifiers must be non-toxic Parenteral For intravenous, o/w, drug solubilised in oil phase Always sterile Do not cause toxicity and embolism, therefore choice of emulsifiers very limited Droplet size kept average 0.2 µm 4  Topical o/w or w/o, includes semisoids cream, ointment, cream Droplet size not so particular (around 1µm) Wide variety of choice of emulsifiers Non-sterile Emulsion formation Recap (Surfactants): When a small quantity of oil is layered on water, experience tells us that the oil will not disperse as droplets through the water unless we start mixing: Oil Mix H2O ΔG* = γΔA Surface area Gibbs free energy Surface tension  Surfactant at the interface reduces γ, and therefore reduces the possibility of collisions because ………… (what happened to ΔG*?) Oil Without surfactants H2O With surfactants 7 Illustration of various emulsion destabilised processes. Factors affecting the formulation of emulsions Formulators must minimize globule coalescence and other physical changes (emulsion destabilization). requires the careful use of emulsifying agents to reduce the interfacial tension. Selection of emulsifiers - classified into three major groups: 1. Surface active agents – Cetrimide, sodium laureth sulphate, cetomacrogol 2. Finely divided solids – Mg (OH)2 and Al (OH)3, bentonite 3. Hydrophilic colloids – Methylcellulose, acacia, gelatin, poloxamer, carbomer 9 Selection of the oil phase 1. The use and desired physical properties of the product 2. The potential toxicity of the oil relative to the route of administration 3. The solubility of active product in the oil relative to phase volume ratio 4. The consistency of the product and any possible incompatibilities Variety of substances have been used including fixed oils (corn, olive, soybean, peanut), aliphatic hydrocarbons, beeswax, long- and medium- chain glycerides, fatty acids and alcohols 10 HLB system Hydrophile-Lipophile Balance (HLB) system Hydrophilic–lipophilic balance (HLB) is the balance of the size and strength of the hydrophilic and lipophilic moieties of a surfactant molecule. A value to select the appropriate emulsifier to produce a stable emulsion. ONLY FOR NON-IONIC SURFACTANTS Tween 60 (HLB =14.9) Span 60 (HLB =4.7) HLB range Uses 0-3 Anti foaming agents 3-6 w/o emulsifying agents 7-9 Wetting and spreading agents 8-18 o/w emulsifying agents 15-20 solubilisers.  HLB Values of some Surfactants Surfactant HLB Surfactant HLB Sorbitan trioleate (Span 85) 1.8 Polyoxyethylene sorbitan 10.5 Sorbitan tristearate (Span 65) 2.1 tristearate, (Tween 65) Sorbitan sesquioleate (Arlacel 83) 3.7 Polyoxyethylene sorbitan trioleate, 11.0 (Tween 85) Glyceryl monostearate, NF 3.8 Polyethylene glycol 400 11.6 Sorbitan monooleate, NF, (Span 80) 4.3 monostearate Sorbitan monostearate, NF, (Span 60) 4.7 Polysorbate 60, NF, (Tween 60) 14.9 Polyoxyethylene monostearate Sorbitan monopalmitate, NF, (Span 40) 6.7 15.0 (Myrj 49) Sorbitan monolaurate, NF, (Span 20) 8.6 Polysorbate 80, NF, (Tween 80) 15.0 Polysorbate 40, NF, (Tween 40) 15.6 Polysorbate 20, NF, (Tween 20) 16.7 Required HLB According to the HLB System, all fats and oils have a Required HLB or RHLB. For example, if we wanted to emulsify Soybean Oil, which has a required HLB of 7, we would need to use an emulsifier or blend of emulsifiers that had an HLB of 7 ± 1. Required HLB for oil phases International Nomenclature of Cosmetic Ingredients (INCI)  HLB calculation FACULTY OF PHARMACY JALAN RAJA MUDA ABDUL AZIZ UNIVERSITI KEBANGSAAN MALAYSIA 50300 KUALA LUMPUR NAME: RN: DATE: 23/4/2023 ADDRESS: AGE: SEX: Mineral Oil 30 g 1) Need to find out about Lanolin 2g ‘required HLB for oil phase. Cetostearyl Alcohol 3g Emulsifying wax 5g 2) Need to use HLB to Glyceryl monostearate calculate the amount of Tween 40 Tween 40 and glyceryl Purified water to 100 g monostearate Sig. Apply prn. Dr Siva Dermatology Specialist Hospital Kuala Lumpur HOW TO PREPRARE THIS LOTION? WHAT METHOD TO USE? STEP 1: Calculate the Required HLB of the oil phase of the lotion Representation of the oil phase in the entire formula = 30+2+3= 35 Representation of different components in the oil phase: Mineral Oil = 30/35 = 0.86 parts of the oil phase. From prescription: Lanolin (Anhydrous) =2/35 = 0.06 parts of the oil phase. Mineral Oil 30 g Cetyl Alcohol = 3/35 =0.086 parts of the oil phase. Lanolin 2g Cetostearyl Alcohol 3 g HLB of Mineral Oil = 10.5 HLB of Lanolin (Anhydrous) = 10 HLB of Cetyl Alcohol = 15.5 Required HLB x Fraction of oil Phase: Mineral Oil = 10.5 x 0.86 = 9.03 Lanolin (Anhydrous) = 10 x 0.06 = 0.6 Cetyl Alcohol = 15.5 x 0.086 = 1.3 Required HLB of the oil phase = 9.0+0.6+1.3 = 10.9 Answer: Required HLB of the oil phase is 10.9 (~ 11) STEP 2: In what proportion should Tween 40 and glyceryl monostearate be blended to obtain a “Required HLB” of 11? HLB of Tween 40= 15.6 HLB of Glyceryl monostearate= 3.8 Previously, we know that the ‘Required HLB’ for the oil phases = 11 Let x be % of Tween 40 in the mixture and 100-x the % of glyceryl monostearate. (15.6 x) + 3.8 (100-x) = 11 From prescription: 100 Emulsifying wax 5g (Glyceryl monostearate + Tween 40) 15.6x +380 – 3.8x = 1100 11.8 x = 720 x =61 % Tween 40 : 5g x 61% = 3.05g Glyceryl monostearate : 5g – 3.05g = 1.95 g