Buffered aspirin

ASPiRiN, BUFFERED The addition of small amounts of antacids may decrease Gl irritation and increase the dissolution and absorption rates of these products. Dosing is the same as with unbuffered aspirin. 

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. 

Some applications of buffers. Many products, including aspirin and blood plasma, are buffered. Buffer tablets are also available in the laboratory (far right to make up a solution to a specified pH. 

G. Levy, J. R. Leonards, and J. A. Procknal, Development of in vitro dissolution tests which correlate quantitatively with dissolution rate-limited drug absorption in man, J. Pharm. Sci., 54, 1719-1722 (1966). K. A. Javaid and D. E. Cadwallader, Dissolution of aspirin from tablets containing various buffering agents, J. Pharm. Sci., 61, 1370-1373 (1972). 

KA Javaid, DE Cadwallader. Dissolution of aspirin from tablets containing various buffering agents. J Pharm Sci 61 1370-1373, 1972. 

Aspirin, plain, buffered, or 325-650 mg every 4-6 hours for pain antiin- 3,600 ... 

Aspirin hydrolysis CTABr and cetylpyridinium chloride + NaOH or buffer. Enhancement at high and inhibition at low pH Broxton, 1982... 

When aspirin was partitioned between buffers pH 1-7 and octyl alcohol, partition coefficients ranging from k=17.7 (pH 1) to k=0.025 (pH 7) were obtained.70 Earlier, coefficients of 0.32 in toluene water and 1.81 in chloroformiwater were determined.71... 

Aspirin can be separated from salicylic acid by ionophoresis at a pH of 4-5.1 8 Separation of aspirin in combination products has been achieved with paper strip electrophoresis, using buffers at pH 2-8 and a 200 V. applied potential.11 9 Aspirin was separated from metabolites by paper electrophoresis in a phthalate buffer of pH 3.2 and an ionic strength of 0.0125-0.0500.150... 

Some aspirin products are sold in buffered form. Infer the reasoning behind this practice. Is there clinical evidence to support it To find out, go to the web site above and click on Web Links. Conduct further research to investigate whether there is more recent evidence either in support of or disproving the effectiveness of buffering aspirin. 

Tablets 325 mg with buffers (ofc) Various, Bayer Buffered Aspirin (Sterling Health), Magnaprin (Rugby), Regular Strength Ascriptin (Aventis), Bufferin (Bristol-Myers), Asprimox (Invamed), Adprin-B (Pfeiffer), Asprimox Extra Protection for Arthritis Pain (Bristol-Myers), Buffex (Roberts Med.)...

Tablets, effervescent 325 and 500 mg with buffers (ofc) Aika-Seitzer with Aspirin, Alka-Seltzer Extra Strength with Aspirin (Miles)...

Mi prophyiaxis - 300 or 325 mg/day. This use applies to solid oral doseforms (buffered and plain) and to buffered aspirin in solution. 

In a high-pressure liquid chromatography assay of aspirin tablets, 10 extracts are made and the extracts are diluted with mobile phase solution, which consists of acetonitrile/0.1 M sodium acetate buffer pH 4.5 (10 90) and analysed sequentially. If the rate constant for the degradation of aspirin in the mobile phase is O.OfOl h " at room temperature how long can the andyst store the solutions at room temperature before the degradation of the analyte is greater than 0.5% ... 

The assay is more or less the same as that described for the paracetamol tablets except that the tablets are extracted with 0.05 M sodium acetate buffer pH 4.4. The calibration standard solutions are prepared so that they contain both aspirin and paracetamol in 0.05 M sodium acetate buffer pH 4.4 in the concentration range 1.0-1.5 mg/100 ml. 

Aspirin is available as capsules, tablets, enteric-coated tablets (Ecotrin), timed-release tablets (ZORprin), buffered tablets Ascriptin, Bufferin), and as rectal suppositories. Sodium salicylate is available genericaUy. Other salicylates include choline salicylate (Arthropan), choline magnesium trisalicylate (Trilisate), and magnesium salicylate Momentum). 

The reactions in Table 13.8 show that carbon dioxide is a common product in many neutralization reactions. This is clearly displayed when a drop of vinegar (acetic acid) is added to baking soda (sodium bicarbonate). Some aspirin includes an antacid in their formulation to neutralize some of the acidity imparted by the aspirin (acetylsalicylic acid). These are commonly referred to as buffered aspirins. 

Many aspirins are advertised as buffered aspirin, and this has led to the misunderstanding that these aspirin are buffers. In reality, as mentioned previously, buffered aspirins actually contain an antacid to reduce the problems brought on by the effects of aspirin, which is the acid called acetylsalicylic acid. Because of its widespread use and importance to humans, let s take an extended look at the history and chemistry of aspirin. 

Aspirin s original use as an analgesic, antipyretic, and to reduce inflammation continues to this day, and more recently some evidence has been found that it may lessen the chance of heart attacks due to its effect as a blood thinner. Just as aspirin continues to provide the same benefits as a century ago, it also produces some of the same problems. The major problem is that it can upset the stomach. In the acidic environment of the stomach, aspirin can diffuse through the protective mucous lining of the stomach and rupture cells and produce bleeding. Under normal doses, the amount of blood loss in most individuals is only a milliliter or two, but in some individuals who take heavy doses bleeding can be severe. To counterattack this side effect, manufacturers include an antacid such as aluminum hydroxide and call the aspirin a buffered aspirin. As noted previ-... 

Many examples are present in the scientific Uterature underlining the effort in producing kinetic data [9—11]. The Edwards historical study that started the investigation on the mechanism of the hydrolysis of aspirin required hundreds of kinetic experiments [12,13]. Several examples are reported by Carstensen [1] in his review on the subject where, beside the large space dedicated to the determination of the pH-rate profile, the effect of temperature, ionic strength, buffer concentration, and dielectic constant on the stability of drugs was treated. 

Figure 14 shows the variable-pH kinetic (VpHK) profile obtained spectrophoto-metrically for the reaction of hydrolysis of aspirin with pH varying in the range 2-10 at T = 342.5 K. The variable-concentration conditions were realized by adding a concentrated solution of NaOH (0.6 M) to the thermostatted reaction vessel containing the aqueous solution of acetylsahcylic acid and a buffer composed of acetic acid (0.01 M), fosforic acid (0.01 M), and boric acid (0.01 M). In this way an almost linear increase of pH was generated. The absorbance was read by an optical fiber cell and stored in a computer. The pH was monitored by a pH sensor connected to a computer. 

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,... 

First, mobile phase and column we saw that most of the small molecule separations could be made on a C18 column in An/buffer water, with the exception of charged molecules and carbohydrates, which are too water soluble. We saw a range of polarity from fat-soluble vitamins, steroids, triglycerides, chlorinated pesticides eluting in 60-80% An/water, to carbamate, phosphate pesticides, anticonvulsants, antidepressants at 40-50% An/water, to nucleosides, nucleotides, aspirin, and water-soluble vitamins at 5-10% An/water. If you know something about the compound s structure or its solubility, you have a good clue as to what mobile phase can be used for its separation. 

The formation of these ternary luminescent lanthanide complexes was the result of displacement of the two labile metal-bound water molecules, which was necessary because the energy transfer process between the antenna and the Ln(III) metal centre is distance-dependent. This ternary complex formation was confirmed by analysis of the emission lifetimes in the presence of DMABA and showed the water molecules were displaced by a change in the hydration state q from 2 to 0, with binding constants of log fCa = 5.0. The Eu(III) complexes were not modulated in either water or buffered solutions at pH 7.4. Lifetime analysis of these complexes showed that the metal-bound water molecules had not been displaced and that the ternary complex was not formed. Of greater significance, both Tb -27 and Tb -28 could selectively detect salicylic acid while aspirin was not detected in buffered solutions at pH 7.4, using the principle as discussed for DMABA where excitation of the binding antenna resulted in a luminescent emission upon coordination of salicylic acid to the complex. 

Aluminum compounds are used in many diverse and important industrial applications such as alums in water-treatment and alumina in abrasives and furnace linings. They are found in consumer products such as antacids, astringents, buffered aspirin, food additives, and antiperspirants. Powdered aluminum metal is often used in explosives and fireworks. To learn more about the properties and uses of aluminum, see Chapters 3 and 4. 

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