Topical vehicles

Topical NSAID preparations are used infrequently in North America. Theoretically, administration via a topical vehicle targets the joints involved and decreases systemic exposure. Randomized, controlled trials, typically of less than 4 weeks duration, have suggested that topical NSAIDs are superior to placebo in relieving OA pain in the first 2 weeks of treatment, but the effect may decline over time.33 Moreover, data are lacking to quantify the theoretical safety advantage of administering NSAIDs topically. 

Chitosan has been shown to increase precorneal drug residence times. The cationic chitosan slows tear drainage by increasing viscosity and by mucoadhesion with the negatively charged mucin. Up to a threefold increase of the corneal residence time has been achieved by the addition of chitosan to topical vehicles [5]. Carbomer gels at 0.3% have also been shown to be effective in prolonging the tear film break-up time [6]. Hyaluronic acid has been reported to... 

Surfactants—traditionally common constituents and stabilizers of topical vehicles, ranging from hydro-phobic agents such as oleic acid to hydrophilic sodium lauryl sulphate— have been tested as penetration enhancers to improve transdermal drug delivery. 

Barry BW. Continuous shear, viscoelastic and spreading properties of a new topical vehicle, FAPG base. J Pharm Pharmacol 1973 25 131— 137. 

Few studies have been carried out on nonaqueous emulsions, but these can be useful as topical vehicles or reservoirs for the delivery of hydrolytically unstable dmgs. Systems such as castor oil or propylene glycol in silicone oil can be formulated using silicone surfactants the HLB number clearly does not help in the formulation, especially if the continuous phase has low polarity. The key to stabilisation lies in the sufficient solubility of the emulsifier in the continuous phase. 

A comprehensive account of the pharmaceutics and biopharmaceutics of topical preparations is not possible here. This section has therefore been deliberately restricted in scope to deal with the physicochemical principles involved in the process of treating the skin or in systemic medication by the transdermal or percutaneous route. Formulation of topical vehicles for the potent dmgs applied to the skin is now an exact art. It is readily demonstrated that the... 

Poulsen BJ, Young E, Coquilla V, et al. Effect of topical vehicle composition on the in vitro release of fluocinolone acetonide and its acetate ester. J Pharm Sci 1968 57(6) 928-933. 

Cerchiara, T, Luppi, B., Bigucci, F., Orienti, I., Zecchi, V. (2002). Physicalty cross-linked chitosan hydrogels as topical vehicles for hydrophilic drugs. 1. Pharm. Pharmacol.. 54,1453-1459. 

See Transit Vehicles DOE/EERE postings at http //www.eere.energy.gov/topics/vehicles.html. 

Cal K (2006) Skin penetration of terpenes from essential oils and topical vehicles. Planta... 

M. Brown, and S. Jones, Hyaluronic acid A unique topical vehicle for the localized delivery of drugs to the skin, /. Eur. Acad. Dermatol. Venereal, 19 (3), 308-318,2005. 

B. Euppi, T. Cerchiara, F. Bigucci, A.M. Di Pietra, I. Orient , and V. Zecchi, Crosslinked poly(methyl vinyl ether-co-maleic anhydride) as topical vehicles for hydrophilic and lipophilic drugs. DrugDeliv., 10 (4), 239-244, 2003. 

Sorbitan sesquioleate emulsions of petrolatum and wax are used as ointment vehicles in skin treatment. In topical appHcations, the inclusion of both sorbitan fatty esters and their poly(oxyethylene) derivatives modifies the rate of release and promotes the absorption of antibiotics, antiseptics, local anesthetics, vasoconstrictors, and other medications from suppositories, ointments, and lotions. Poly(oxyethylene(20)) sorbitan monooleate, also known as Polysorbate 80 (USP 23), has been used to promote absorption of ingested fats from the intestine (245). 

Darrow, K.G., Idght Duty Vehicle Full Fuel Cycle Emissions Analysis Topical Report, Gas Research Institute Report GRI-93/0472 (1994)... 

The chapter on Radioactive chemicals (Chapter 11) has been updated. Considerations of safety in design (Chapter 12) are presented separately from systems of work requirements, i.e. Operating procedures (Chapter 13). Tlie considerations for Marketing and transportation of hazardous chemicals are now addressed in two separate chapters (Chapters 14 and 15). Chemicals and the Environment are now also covered in two chapters (Chapters 16 and 17) to reflect the requirement that the impact of chemicals on the environment should be properly assessed, monitored and controlled. Although a substantial contribution to atmospheric pollution is made by emissions from road vehicles and other means of transport, and this is now strictly legislated for, this topic is outside the scope of this text. Chapter 18 provides useful conversion factors to help with the myriad of units used internationally. 

Therapeutic Function Topical protectant ophthalmic vehicle Chemicel Name Callulose 2-hydroxypropyl ether Common Name Hyprolose Structural Formula ... 

Topical corticosteroids vary in potency, depending on tiie concentration of the drug (percentage), the vehicle in which the drug is suspended (lotion, cream, aerosol spray), and the area to which the drug is applied (open or denuded skin, unbroken skin, thickness of the skin over tiie treated area). 

Kimbrough-Green CK, Griffiths CE, Finkel LJ, et al (1994) Topical retinoic acid (Tretinoin) for melasma in black patients-a vehicle controlled clinical trial. Arch Dermatol 130 727-733... 

Griffiths CE, Finkel LJ, Ditre CM, et al (1993) Topical tretinoin (retinoic acid) improves melasma a vehicle-controlled, clinical trial. Br J Dermatol 129 415-421... 

Griffiths CE, Kang S, Ellis CN, Kim KJ, Finkel LJ, Ortiz-Ferrer LC, White GM, Hamilton TA,Voorhees JJ (1995) IVvo concentrations of topical tretinoin (retinoic acid) cause similar improvement of photoaging but different degrees of irritation. A double-blind, vehicle-controlled comparison of 0.1% and 0.025% tretinoin creams. Arch Dermatol 131 1037-1044... 

Griffiths CEM, Goldfarb MT, Finkel LJ, et al (1994) Topical tretinoin (retinoic acid) treatment of hyperpigmented lesions associated with photoaging in Chinese and Japanese patients a vehicle-con-trolled trial. J Am Acad Dermatol 30 76-84... 

Fitzpatrick RE, Rostan EF (2002) Double blind, half-face study comparing topical vitamin C and vehicle for rejuvenation of photodamage. Dermatol Surg 28 231-236... 

Leyden JJ, Grove G, Zerweck C (2004) A doubleblind, comparative facial tolerance study of a new 10% sodium sulfacetamide 5% sulfur aqueous gel (in a 10% urea vehicle) vs a 10% sodium sulfacetamide 5% sulfur topical suspension in rosacea acne subjects with sensitive skin. In Abstract of the 62nd Annual Meeting of the American Academy of Dermatology. Washington DC, February 6-11,2004. Abstract P66... 

It is possible, artificially, to so draw the boundaries of a process to give the appearance that waste is not produced. However, a simple examination of the inputs and outputs (and their origin) for any process will show where such wastes are produced. A topical example of this misunderstanding is represented by the mistaken belief that electric vehicles (whether battery- of fuel-cell driven) are non-polluting compared to those powered by the internal combustion engine (Figure 1.4). For any process, therefore, there needs to be a full... 

Theoretically, the risk of serious GI adverse events should be less than with oral NSAIDs, but long-term studies evaluating these events are lacking.38 Studies comparing topical NSAIDs with other topical products, including counterirritants, are also needed.35 Local cutaneous adverse reactions (e.g., erythema, pruritus, and irritation) occur in 1% to 2% of patients and may be due in part to the vehicle used.38... 

Topical agents may be incorporated into various vehicles including ointments, creams, gels, lotions, foams, pastes, and shampoos. Ointments provide occlusion which may increase... 

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