Oral liquids definitions

After mentioning the relevant definitions this chapter firstly discusses the assessment of prescriptions for oral liquids, especially if inadequacy of the corresponding oral solid is the reason for the request. Also the choice between solutions and suspensions should be made carefully. 

Erosion is defined as the loss of hard tissue by chemical means not derived from bacteria, i.e. the dissolution of hard tissue by acid where the acid source is not the oral bacteria [5], Erosion may be caused by either intrinsic (e.g. stomach acid) or extrinsic (e.g. dietary) sources. Erosion is often associated with the consumption of acid products, such as fruits or acid beverages, or with medical conditions where reflux of acidic into the oral cavity is present. Interestingly, the term erosion is widely used in other fields where the definition is rather different. For example, in the field of tribology, erosion refers to the loss of material from a surface by solid or liquid impacts [6], In the classical tribological definitions, the mechanism dentists refer to as erosion would be described as corrosion, or tribo-chemical wear. 

The second edition consists of an introduction, four sections, and two appendices. (The appendices present examples and are not part of the consensus document.) Section 1 identifies the scope of the standard and section 2 lists definitions for particular terms. Thus, paraphrasing, adequate ventilation refers to a condition in which air contaminant concentrations are below levels that cause injury or illness, or, that the vapors of flammable liquids are well below the lower flammable limit. A toxic chemical has an oral LD50 for edbino rats greater than 50 mg/kg but not greater than 500 mg/kg, or a 24 hr. skin contact LD50 for albino rabbits more than 200 mg/kg but not more than 1000 mg/kg, or an inhalation LC50 for albino rats more than 200 ppm but not more than 2000 ppm of gas or vapor or more than 2 mg/f but not more than 20 mg/f of dust or mist, provided that such exposures are reasonably likely to be encountered by humans in their use of the chemical. 

The metabolic clearance of NCEs is most often studied with a combination of in vitro and in vivo approaches. There are several in vivo approaches that can be used to study metabolism in preclinical species, and these along with in vitro results can often shed mechanistic insight onto the problems associated with rapid metabolic clearance and incomplete oral bioavailability due to first-pass metabolism. Modern liquid chromatography tandem mass speetrometry (LC—MS/MS) measurement of plasma drug eoneentrations provide a rapid tool to assess oral bioavailability of new eandidate eompounds and allows for early definition of bioavailability problems. When bioavailability eoneems do arise, there are several avenues discussed below that can be followed to isolate the factor(s) limiting the oral delivery of a compound. 

Powders for the preparation of oral drops generally conform to the definition of Oral powders. They may contain excipients to facilitate dissolution or suspension in the prescribed liquid or to prevent caking. After dissolution or suspension, they comply with the requirements for oral drops. 

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