Tablet formulation aspirin

The source of the raw materials can greatly influence hydrolytic reactions. This is exemplified by Gold and Campbell [54] where talc obtained from different sources impacts markedly on the overall stability of the aspirin tablet formulation. This is possibly attributable to the effect of different types and amounts of surface impurities, which are dissolved in the adsorbed moisture layer, where they subsequently react with the API. It could also influence the pH of the micro-environment. 

In the present experiment, we measure the amount of the active ingredient, acetylsalicylic acid (see also Experiment 35), in common aspirin pills. Companies use different fillers and in different amounts, but the active ingredient, acetylsalicylic acid, must be the same in every aspirin tablet. We separate the acetylsalicylic acid from the filler based on their different solubilities. Acetylsalicylic acid is very soluble in ethanol, while neither starch, nor other polysaccharides, or even mono- and disaccharides used as a fillers, are soluble in ethanol. Some companies may use inorganic salts as fillers but these too are not soluble in ethanol. On the other hand, some specially formulated aspirin tablets may contain small amounts of ethanol-soluble substances such as stearic acid or vegetable oil. Thus the ethanol extracts of aspirin tablets may contain small amounts of substances other than acetylsalicylic acid. 

Fig. 3 (a) The XRD pattern of acetaminophen powder, (b) The XRD pattern of aspirin powder, (c) The XRD pattern of caffeine powder, (d) The XRD pattern of a powdered tablet formulation containing acetaminophen, aspirin, and caffeine (Excedrin ). (From Ref... 

From 1982 through 1985, few NIR analyses of dosage forms were published. Since 1986, there have been many articles. The first was a 1986 paper by Ciurczak and Maldacker [33] using NIR for tablet formulation blends, examining the use of spectral subtraction, spectral reconstruction, and discriminant analysis. Blends were prepared where actives—aspirin (ASA), butalbital (BUT), and caffeine (CAF)—were omitted from the formulation or varied over a range from 90 to 110% of label strength. 

It is clear from Figure 9.16 that aspirin absorption is more rapid from solution than from tablet formulations. This rapid absorption of aspirin is an indication that the rate of absorption is dissolution rate limited. A general relationship describing the dissolution of a drug was first reported by Noyes and Whitney (38). The equation derived by those authors is as follows ... 

More examples can be foimd in references. In two traditional sodium aspirin tablet formulations, stearic acid and magnesium stearate are used as lubricant in the concentration of 1.5% and 0.3%, respectively [12]. 

Uses. Aspirin has analgesic, antiinflammatory, and antipyretic activity. It is used for the reHef of less severe types of pain, such as headache, neuritis, acute and chronic rheumatoid arthritis, and toothache. Aspirin can be purchased in a variety of OTC and prescription dosage forms made and formulated by many companies. Tablets, ie, buffered, plain, or enteric-coated, are the most familiar in the United States, but other forms such as powder and effervescent formulations are of considerable importance in other parts of the world. 

RH Blythe, GM Grass, DR MacDonnell. The formulation and evaluation of enteric coated aspirin tablets. Am J Pharm 131 206-216, 1959. 

The market for aspirin grew at a rapid rate, with sales in the United States reaching 2 billion/year in 1990, This represents 1600 tons of the drug, or 80 million tablets. Within recent years, some aspirin has been formulated with other materials. These include buffers for reducing stomach irritation experienced by some people who consume aspirin. Also within the last decade or so. other nonsteroidal anti-inflammatory drugs (NSAIDs) have been introduced into this highly competitive marketplace,... 

Most of the oxycodone drugs—which include the drug alone or in combination with aspirin or acetaminophen—are available in tablet form. For patients who have trouble swallowing or who cannot take the tablet form for other reasons, the drug is available in a highly concentrated flavored liquid solution. The appropriate dose of the liquid is measured into a dropper either by a nurse or by the patient. Often, the liquid may be added to semi-soft foods such as applesauce or pudding to help disguise its bitter taste. Those who use liquid formulations of oxycodone should be aware that some of them may contain alcohol. 

Aspirin is commercially available in numerous formulations (Table 7-1). It is compounded as a tablet, an enteric-coated tablet, a controlled-release tablet, and as a suppository. Enteric-coated aspirin, which decreases GI tract irritation, is recommended for chronic use but is rarely required for the treatment of acute ocular pain, which usually resolves over several days. Likewise, controlled-release aspirin, because of its relatively long onset of action, is not recommended for treatment of acute ocular pain. 

The primary limitation on the use of direct compression is that it depends on the fluidity and compressibility of a tablet diluent. Therefore, it cannot be used for low potency, high dose active ingredients where the inclusion of sufficient diluent in the formulation to permit direct compression would lead to unacceptably large tablets. Thus, active ingredients such as paracetamol and aspirin do not lend themselves to the direct compression process. However, as stated earlier, such ingredients are often available in pregranulated form. 

Many examples of the effects of tablet excipients on dmg decompositions are reported in the pharmaceutical literature. Chemical interaction between components in solid dosage forms may lead to increased decomposition. Replacement of the phenacetin in compound codeine and ARC tablets by paracetamol in NHS formulations in Australia in the 1960s (because of the undesirable side-effects of phenacetin), led to an unexpected decreased stability of the tablets. The cause was later attributed to a transacetylation reaction between aspirin and paracetamol and also a possible direct hydrolysis of the paracetamol (Scheme 4.15). 

Salicylic acid as an impurity was investigated in 12 different brands of aspirin formulations readily available in Lagos (Nigeria). The HPLC method adopted for the investigation involved a mobile phase of methanoi/water (20/80, v/v) adjusted to pH 2.5 with phosphoric acid and was run on a 50 mm column monitored at 240 nm. The limit of detection for salicylic acid was 5 ng. Only three of the formulations showed the presence of salicylic acid impurity and all these contained salicylic acid in excess of the USP 1980, limit of 0.3% salicylic acid per tablet (52). 

The majority of medicines today are formulated as tablets [1], Tablets are formulated rapidly and economically, and they have high patience compliance. Also, many compounds, such as aspirin, degrade rapidly in solution and are formulated in solid dosages to increase stability [2]. Drug substances that are oils, liquids, and solids may be formulated into capsules, tablets, lyophiles, creams, or microsuspensions. Administration may be through ingestion, injection, topical application, inhalation, and other routes. The reader may consult other texts for discussion of formulation options [1,3]. Formulations are selected for stability and the ability to best deliver the active agent to the affected area of the patient or consumer. 

A degradant is defined as a compound that cumulates during the storage of bulk drug or finished formulation. For example, the vinegar-like odor of old aspirin tablets is due to acetic acid, which is a degradant due to hydrolysis of acetylsalicylate, which is an ester. 

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