Usage period

We can divide Fixed Step Counters on two classes by usage period of step weight value (W) ... 

Miscellaneous 4-week usage period Fatiguing index Pilot group Continuous exposure SLS/irritation as adjuvant... 

Retain quality throughout the shelf life and usage period. 

There is also usually a recommended period of time during which the purity of an analytical standard is considered to be assured if the standard is properly stored, typically from 2 to 5 years, and this will normally be given on the certificate of analysis provided with the standard. If no expiry date is provided with the standard, then it is the responsibility of the laboratory to establish the optimum storage conditions and a maximum time period for which the standard may be used. At the end of this period, the standard should be replaced. However, the usage period may be extended if the laboratory establishes a procedure to recertify the standard with tests that show that no changes in the purity and composition of the standard have occurred. Procedures used to establish or extend expiry dates for standards should be documented. 

Up to this point, the anemometer on the finish of the fast and accurate verification could be attached to anemometer calibration box with the above-mentioned corrective curve anemometer and the formula, to be used together with the anemometer in the normal usage period until the next correction. 

The pH of antacid suspensions is between 7.7 and 8.2. This pH range is very unfavourable for the stability and effectiveness of methyl parahydroxybenzoate and no other preservatives are available for that pH range. Propyl parahydroxybenzoate can be added but additional measures are needed to achieve a reasonable shelf life the use of raw materials with a low bioburden, preventing contamination during preparation, storage in the fridge, small bottles, limited usage period. 

For standard nasal preparations that are not chemically stable, the maximum shelf life must be indicated in the formulary. For chemically and physically stable fatty nasal ointments that contain water, the maximum shelf fife is set at 3 years at < 25 °C, (not in a freezer). The usage period after opening the container may be 3 months (see Sect. 22.7.1). 

Ear drops for the external canal in non-aqueous vehicles (glycerol, propylene glycol or macrogol) do not need to be sterile. As the water activity in these solvents is very low, the addition of a preservative is unnecessary. Water is the solvent in the ear drops with aluminium acetate or acetotartrate (Table 9.2). The active substance in this concentration has such strong antimicrobial properties, that the formulation complies with the test on the efficacy of microbial preservation of the Ph. Eur. without an additional preservative [22]. However in the tenfold diluted ear drops (used if physicians want to avoid the risk of ototoxicity at all) the preservative properties are insufficient, due to the low concentration. Therefore the shelf life as well as the usage period are much shorter than for the undiluted preparation [23],... 

For chemically stable ear drops a maximum shelf life of 2 years at <25 °C, not refrigerated, is generally cmisidered acceptable (see Sect. 22.7). For standard ear drops that are not chemically stable, the maximum shelf life is specific and validated, and should be indicated in the relevant monograph in the formulary. The maximum shelf life is to be used mily for the unopened container. Once opened, the usage period for patients may be arbitrarily set at 6 months at <25 C, not refrigerated, provided that the end of this period is not beyond the expiry date. 

For sterile aqueous preserved ear drops the usage period is set at maximum 1 month after opening. 

Suppositories prepared as extemporaneous preparations following a non-standardised formula, having an unknown chemical or physical stability, should immediately be dispensed to the patient who gets a maximal usage period of 1 month only (see Sect. 22.7.2) if classified as semisolid preparation. If the patient only takes a suppository on demand a usage period of 1 month is very short and it may be justified to consider fiiem to be comparable to a dry dosage form with an arbitrarily chosen maximum usage period of 6 months. 

When performing stability studies on medicines to determine shelf-life and usage periods, it is shown that chemical degradation may be fairly predictable but shelf life and usage periods may be influenced by less predictable causes. Changes that can be observed by the patient offer another perspective. The last section of the chapter provides advice on storage conditions, shelf life and usage periods of pharmacy preparations. 

Stability Chemical degradation Microbial degradation Shelf life Storage Hydrolysis Oxidation Photolysis Stability testing Usage period... 

The shelf life of a preparatiOTi is usually constructed of two consecutive components shelf life in the intact package and the usage period after opening of the package. Their definitions are ... 

Maximum usage periods for patients after opening the package, for medicines in multidose containers, with a standardised formula, are given in Table 22.15. These maximum usage periods are only valid within the shelf life of the preparation. 

At the time of dispensing in the pharmacy, the maximum usage period must be sufficient for the duration of the prescribed therapy. 

Table 22.15 Assigned usage periods for dosage forms ...

Dosage form Maximum usage period for the patient... 

Extemporaneous preparations, with unknown or uncertain chemical or physical stability, carmot be kept on stock in the pharmacy. They have a maximum usage period according to Table 22.15, but this period is not more than 1 month for liquid and semisolid preparations, and not more than 6 months for dry forms. If the formula is similar to a standardised one, the maximum shelf life of that standardised formula can be used. 

Fig. 22.3 Flow chart for the assignation of usage periods of dosage forms in multidose containers...

Usage period according to table 22.5 with a maximum of 1 month for liquid or semi-solid forms and... 

Table 22.16 Usage periods in the pharmacy of Stock packages of cutaneous bases...

Type of semi-finished product Usage period in pharmacy... 

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