Caffeine Aspirin

I. M. Jalal and S. I. Sa sa, Simultaneous determination of dextro-propoxyphene napsylate, caffeine, aspirin and salicylic acid in pharmaceutical preparations by reversed-phase HPLC, Talanta, 37 1015 (1984). 

At this solvent composition the peaks should be partially separated. The elution order is caffeine, aspirin, and phenacetin. A 5-jaL injection might be used if a column containing 5 or 10 /am particles (15 or 30 cm length) is used and the peak heights are too high. 

Caffeine Aspirin Increased rate of absorption of aspirin No action required... 

SOS chromotest sfiA lacZ, alkaline phosphatase Benzofurans, naphtafurans, fungal toxins, MMC, NCS, MMS, EMS, DMS, DES, b-propiolactone, propane sultone, DMN, DEN, MNNG, B[a]P, 4NQO, DMSO, NaCI, Caffeine, Aspirin E. coli 50... 

Simultaneous dyphylline, theophylline, caffeine, aspirin, salicylic acid, procainamide, N-acetylprocainamide... 

Barbiturates are therapeutically used as sedatives, hypnotics, anesthetics, and anticonvulsants. Virtually all barbiturates on the illicit drug market come from licit sources. There are 12 barbiturates recognized and scheduled by the United Nations and occur mainly as capsules and tablets and in some cases as injectable solutions. Illicit compounds occur as mixtures of barbiturates, or mixed with other drugs such as caffeine, aspirin, codeine, or in some cases heroin (Figure 6). 

Compounds Matter is ultimately composed of atoms, but those atoms are often combined in compoimds. The most important characteristic of a compound is its constant composition. The elements that make up a particular compound are in fixed, definite proportions in all samples of the compound. Compounds Most of the matter we encounter is in the form of compounds. Water, salt, and carbon dioxide are all examples of common simple compounds. More complex compounds include caffeine, aspirin, acetone, and testosterone. 

The analysis of APC tablets (a mixture of aspirin, phenacetin, and caffeine) has been a common undergraduate laboratory experiment. This experiment describes modifications to the standard analysis for APC tablets in which paracetamol (also known as acetaminophen) replaces phenacetin. 

This drug is quite frequently found in headache remedies in com-liination with aspirin and caffeine (APC , PAG ). Although the iniline derivatives show analgetic potency comparable to aspirin,... 

Xanthines such as caffeine (1)> theophylline (aminophylline) (2), and theobromine (3) are a class of alkaloids that occur in numerous plants. The CNS stimulant activity of aqueous infusions containing these compounds has been recognized since antiquity. This has, of course, led to widespread consumption of such well-known beverages as coffee (Coffea arabica), tea (Thea sinesis), mate, and cola beverages (in part Cola acuminata). The annual consumption of caffeine in the United States alone has been estimated to be in excess of a billion kilos. The pure compounds have found some use in the clinic as CNS stimulants. In addition, caffeine is widely used in conjunction with aspirin in various headache remedies. 

High performance liquid chromatography is used for the separation and quantitative analysis of a wide variety of mixtures, especially those in which the components are insufficiently volatile and/or thermally stable to be separated by gas chromatography. This is illustrated by the following method which may be used for the quantitative determination of aspirin and caffeine in the common analgesic tablets, using phenacetin as internal standard where APC tablets are available the phenacetin can also be determined by this procedure. 

Sample mixture. A suitable sample mixture is obtained by weighing out accurately about 0.601 g of aspirin, 0.076 g of phenacetin and 0.092 g of caffeine. Dissolve the mixture in 10 mL absolute ethanol, add 10 mL of 0.5M ammonium formate solution and dilute to lOOmL with de-ionised water. 

Procedure. Inject 1 fiL of the sample solution and obtain a chromatogram. Under the above conditions the compounds are separated in about 3 minutes, the elution sequence being (1) aspirin (2) phenacetin (3) caffeine. Measure peak areas with an integrator and normalise the peak area for each compound (i.e. express each peak area as a percentage of the total peak area). Compare these results with the known composition of the mixture discrepancies arise because of different detector response to the same amount of each substance. 

When linezolid is used with antiplatelet drugs such as aspirin or die NSAIDs (see Chap. 18) diere is an increased risk of bleeding and thrombocytopenia When administered widi die MAOIs (see Chap. 31) the effects of the MAOIs are decreased. There is a risk of severe hypertension if linezolid is combined widi large amounts of food containingtyramine (eg, aged cheese, caffeinated beverages, yogurt, chocolate, red wine, beer, pepperoni). 

Skeletal Muscle Relaxant Combinations Carisoprodol Compound—carisoprodol, aspirin Mexaphen—chlorzoxazone, acetaminophen Lobac—salicylamide, phenyltoloxamine, acetaminophen Norgesic Fbrte—orphenadrine citrate, aspirin, caffeine Norgesic—orphenadrine citrate, aspirin, caffeine Robaxisal—methocarbamol, aspirin Sodol Compound—carisoprodol, aspirin Soma Compound—carisoprodol, aspirin... 

It is added to pain relievers because it enhances the effects of aspirin and because many headaches are caused by caffeine withdrawal. Caffeine closes down blood vessels by competing with adenosine, and helps alleviate the vascular headaches caused by withdrawal. 

Interactions with caffeine and aspirin can increase the effects of ephedrine. Norepinephrine works in part by increasing the levels of cyclic aminomethyl propanol (AMP) in cells. Caffeine inhibits the enzyme that breaks down cyclic AMP. Together, ephedrine makes more cyclic AMP, and caffeine prevents it from breaking down. Aspirin inhibits the receptors that turn off release of norepinephrine. 

Ephedrine by itself has been shown to be ineffective as a weight-loss treatment. Ephedrine combined with either caffeine or aspirin is effective. The effect appears to stem from a combination of appetite reduction and avoidance of the metabolic rate decrease usually associated with a reduced-calorie diet. 

As the solvent mixture also contained 225 mg of tetramethyl ammonium hydroxide pentahydrate per liter at a high water content (75%), the surface of the reverse phase would have been largely covered with the tetramethyl ammonium hydroxide pentahydrate. This would have acted as an adsorbed ion exchange stationary phase. It is clear that the free acids, salicylic acid, acetylsalicylic acid (aspirin) and benzoic acid were retained largely by ionic interactions with adsorbed basic ion exchanger and partly by dispersive interactions with the exposed reversed phase. The acetaminophen and the caffeine, on the other hand, being unionized substances, were retained only by dispersive interactions with the exposed reversed phase. 

Figure 5 Separation of pharmaceuticals, including amines, on strong cation exchange. Column 0.46 x 15 cm Merckosorb SI-60-SCX, 5 p. Eluent 50 mM aqueous ammonium formate-10% ethanol, pH 4.8. Flow 1 ml/min. Temperature 50°C. The peaks are (1) aspirin, (2) paracetamol, (3) phenacetin, (4) caffeine, (5) phenylephrine, (6) salbutamol. (Reproduced with permission of Elsevier Science from Cox, G. B., Loscombe, C. R., Slucutt, M. J., Sugden, K., and Upheld, J. A., /. Chromatogr., 117, 269, 1976).

Barr, H. M., Streissguth, A. P., Darby, B. L., Sampson, P. D., Prenatal exposure to alcohol, caffeine, tobacco, and aspirin Effects on fine and gross motor performance in 4-year-old children. Developmental-Psychology 26(3), 339-348, 1990. 

D Southwell, BW Barry. Pentration enhancement in human skin. Effect of 2-pyrroli-done, dimethylformamide and increased hydration on finite dose permeation of aspirin and caffeine. Int J Pharm 22 291-298, 1984. 

This example will illustrate the quantitative analysis of aspirin (acetylsalicylic acid), phenacetin and caffeine in a mixture. The structures of these three are shown in Fig. 4.4a. 

Analgesic tablets often contain aspirin and caffeine, and we will eventually use the results for the quantitative analysis of a commercial tablet. 

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