Ointments, Creams, Transdermal, Gels

OINTMENTS, CREAMS, PASTE, GELS, TRANSDERMALS PATCHES

OINTMENTS -          Semisolid -          Medicated or unmedicated -          Unmedicated: PROTECTANTS, EMOLLIENTS, LUBRICANTS -
OINTMENT BASES
1.       Oleaginous Base “Hydrocarbon base”	-          Emollient effect -          Occlusive -          Long periods without drying out -          Hard to incorporate with aqueous preparations (water) *Powdered substances: Liquid petrolatum (mineral oil)- use as levigating agent		Petrolatum, USP –purified mix, yellowish, light-amber Yellow petrolatum, jelly     White petrolatum- purified, DECOLORIZED WHITE petrolatum PETROLEUM JELLY …Vaseline   Yellow ointment- Simple Ointment Yellow wax (50 g) + Petrolatum (950 g) *yellow wax: Apis mellifera   White Ointment Uses  WHITE WAX
2.       ABSORPTION BASE	a.        W/O (e.g Lanolin) b.      O/W (e.g Hydrophilic petrolatum)   -Not easily removed because of external phase oil - USEFUL AS ADJUNCTS TO INCORPORATE small vols of aqueous into HYDROCARBON BASE		AQUAPHOR à  Hydrophilic Petrolatum (melt- stearyl alc + whitewax + cholesterol + white petrolatum)     Lanolin, USP -obtain from SHEEP Ovis aries purified waxlike; cleaned, deodorized, decolorized (less 0.25% water)
3.       WATER-REMOVABLE BASE        Water- washable	Oil in WATER O/W -          Easily washed out from skin -          Absorb serous discharges		Hydrophilic OINTMENT ( + parabens, Na lauryl sulphate, water)
4.       WATER-SOLUBLE Bases Greaseless	NO OLEAGINOUS Mostly used for incorporation Of SOLID SUBSTANCES		Polyethylene Glycol Ointment (PEG) -          Polymer of ethylene oxide and water MW less 600- clear 600-1000 - semisolid MW above 1000- white
PREPARATION OF OINTMENTS
1.       INCORPORATION		Mixed until uniform preparation achieved By mortar pestle Unguator-mixing device INCORPORATION OF SOLIDS -          Geometric dilution- small portion of powder is added with a portion of base until uniform -          Levigating- mixing solid in avehicle to make smooth dispersion (e.g mineral oil) -          Pulverization by Intervention- for gummy materials( camphor) INCORPORATION OF LIQUIDS   -          HYDROPHILIC+ enough Hydrophobic= blend; then add to rest HYDROPHOBIC
2.       FUSION		All or some of the components of an ointment are combined by being MELTED together and COOLED with CONSTANT STIRRING until CONGEALED -          Heat labile or volatile: ADDED LAST -          Substance with highest melting point- are heated to their lowest temp they can melt
COMPENDIAL REQUIREMENTS
1.       Absence of		Staphylococcus aureus Pseudomonas aeruginosa
CREAMS -          Semi-solid -          One or more medicinal agents dissolved or dispersed in either W/O or O/W emulsions containing large amounts of WATER, STEARIC ACID, or other oleaginous substances -          After application, water EVAPORATES, leaving thin film of stearic acid -          VS OINTMENTS: EASIER TO SPREAD OR REMOVE
GELS -          Semi-solid systems consisting of dispersion of small or large molecules in an aqueous liquid vehicle rendered jelly like -
Gelling agents		Carbomers : Tragacanths, -methycellulose
Single Phase Gel		Uniformly dispersed throughout the liquid No boundaries between macromolecules and liquid
Two phase system		“Magma” Gel mas  consisting of floccules of small distinct particles Ex: MILK OF MAGNESIA, thixotrope
PASTE -          CONTAIN LARGER AMOUNT OF SOLID (SUCH AS 25%) -          STIFFER THAN OINTMENT -           Ex: Zinc Oxide Paste (LASSAR’s Plain Zinc Paste)
PLASTER -          Solid or semisolid adhesive masses spread on backing paper, fabric moleskin, plastic -          EX: Salicylic Acid plaster (remove corns)
GLYCEROGELATINS -          Plastic masses containing: gelatin (15%); glycerine (40%), water (35%), medicinal substance (10%) -          Ex: Zinc Gelatin (varicose)
TYPES OF PLASTICS
HDPE		Superior moisture barrier, less resilient
LDPE		Soft, resilient, good moisture barrier
Polypropylene (PP)		High level of heat resistance
PET (polyethylene terephthalate)		Transparency; high degree of product compatibility

 

TRANSDERMAL DRUG DELIVERY SYSTEMS -          Facilitate passage of therapeutic quantities of drug substances through the skin and general circulation for their systemic effects -          STRATUM CORNEUM; MAJOR RATE LIMITING BARRIER TO TRANSERMAL DRUG TRANSPORT -          MW 100 TO 800 -          Ideal MW: MW 400 or less Enhance drug delivery by: -          Iontophoresis: delivery of  a charged chemical compound across skin membrane using electric field -          Sonophoresis: High frequency ultrasound -          Ex: Transdermal Scopolamine: for motion sickness -          Nitroglycerin transdermal: Nitro-dur, Nitrodisc, Minitran -                   To avoid tolerance: 12-14 hr patch on; 12 to 14 hrs patch off