Lotions, defined

Patients with photodamage can apply a lotion containing 25% glycolic acid for 6 months. In such cases an increase in total skin thickness of approximately 25% was reported, accompanied by an increased thickness of viable epidermis and dermis, an increased content of acid mucopolysaccharides, a greater collagen density and an improved quality of the elastic fibers. This could be defined as self-treatment. 

A medicine or skin lotion is often described as pH neutral as though it was obviously a good thing. A solution is defined as neutral if it contains neither an excess of solvated protons nor an excess of hydroxide ions. Equation (6.4) tells us the autoprotolysis constant Kw of super-pure water (water containing no additional solute) is 10-14 (moldm-3)2. Furthermore, we saw in Worked Example 6.1 how the concentration of the solvated protons was 10-7 mol dm-3 at 298 K. 

The elbow test involves applying products to the inside of the elbow up to six times per day for three weeks. This is a sensitive area of skin, and easily defined, which is important since this is a selfapplication test. This test is useful for products such as body lotions, etc., and also as a preliminary to a face test, where the skin is more sensitive. Each panellist serves as their own control the test material is applied to one elbow and the control material applied to the other. The panel is balanced according to sex, hand dominance, and initial skin grades of reaction. One half of the panel has the dominant hand allocated to the test material, and the other half has their dominant hand allocated to the control material. The levels of irritation elicited by the test and control treatments are compared. Subjective comments are also taken into consideration. At intervals throughout the treatment period, each site is assessed for visible signs of irritation, for example, erythema and dryness. 

This is the place to start, since most often, analytical chemists are trying to help solve someone else s problem. We need to define the solute and its matrix as well as the nature of the analytical problem. For example, in the world of pharmaceuticals, there are raw material identification and purity determinations, in-process testing, dosage-form determinations, content uniformity, dissolution testing, stability studies, bioavailability, pharmacokinetics, and drug metabolism, to name a few. Each of these analytical problems has its own specific requirements. The matrix can be a raw material, granulation, tablet, capsule, solution, lotion, cream, syrup, dissolution medium, blood serum, urine, or various body tissues and fluids. Similar definitions can be described for virtually any industrial area and problem set. These definitions will help select sample preparation, separation, and detection techniques. 

Within the UK, the term For external use only is used on any preparation intended for external use. The Medicines Act 1968 defines products for external use as embrocations, liniments, lotions, liquid antiseptics, other liquids or gels for external use. 

The majority of creams and lotions are emulsions. An emulsion can be defined simply as two immiscible fluids in which one flquid is dispersed as fine droplets in the other. Homogenized milk is an example of a typical oil-inwater (o/w) emulsion. Alilk fat (oil) is dispersed in water as fine droplets by the homogenization process. The reason the fat does not float to the top immediately is due to the presence of emulsifiers in this case, a milk protein called sodium caseinate as well as several phopholipids. In the case of water-in-oil (w/o) emulsions, water is dispersed as droplets and suspended in the oil phase. The nondispersed liquid or external suspending phase is also called the continuous phase. Mayonnaise, vinegar water dispersed as fine droplets in a continuous phase of soybean oil, is an example of a water-in-oil emulsion. Lecithin from eggs stabilizes the mayonnaise emulsion. 

Weigh defined amount of -CD and 20% sodium hydroxide solution into a triangle flask and agitate until dissolved completely at 60 C. Drop 30 mL EPI into the solution while stirring and keep the reaction to gain a hard gel. Take out the gel and wash it with water and acetone until no chloride ions remain. Filter the lotion, then dry at 60°C for 48 h under vacuum and grind afterwards. The white powder is the crosslinked polymer product. 

Eye lotions are defined as aqueous solutions. Thus active substances must be soluble at the concentration needed. Eye lotions must be sterile. According to Ph. Eur. eye lotions intended for use in surgical procedures or in first-aid treatment do not contain an antimicrobial preservative and are supplied in single-dose containers, see for example an eye lotion with iodinated povidone (Table 10.11). 

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