Aspirin soluble

Effervescent aspirin, soluble aspirin, and soluble aspirin to which sufficient NaHCOs had been added to give it the same buffering capacity as the effervescent preparation, were compared in healthy volunteers. There were no significant differences in plasma salicylate levels at any time after taking these preparations. ... 

Febvre, P. Aiache, J.-M. Bex, J.F. Etude en continu in vivo de la salicylemie du lapin apres ingestion d aspirine soluble sous differentes formes galeniques. C.R. Soc. Biol. 1969, 163, 1160. 

Figure 2 shows the Hansen model calculation results versus experimental data for aspirin solubility in various solvents at room temperature. The Hansen solubility... 

Alpha hydroxy acids (AHAs) are water-soluble substances and thereby penetrate the outermost epidermal skin layers. In contrast, beta hydroxy acids (BHAs) are lipid (fat) soluble and are capable of penetrating to the underlying layers of skin (the dermis) located 1-5 mm below the surface of the skinJ2 Most AHAs are derived from plant materials and marine sources. Commonly used AHAs include malic acid (found in apples), ascorbic acid (a common ingredient in numerous fruits), glycolic acid (a constituent of sugar cane), lactic acid (a component of milk), citric acid (naturally abundant in citrus fruits), and tartatic acid (found in red wine). A common BHA is salicylic acid (an ingredient in aspirin). 

A number of water-soluble calcium salts provide convenient vehicles for the administration of therapeutic anions. Probably the most widely encountered is the acetylsalicylate of soluble aspirin (patented 1935) the urea complex of calcium acetylsalicylate (water-solubility 231 gdm-3 at 310K, pH 4.8 (717)) is also widely used. Other examples include calcium bromide and bromolactobionate (sedatives), calcium 2-hydroxy-3-mercapto-l-propanesulfonateaurate(III) (chrysanol, antiarthritic), and calcium Af-carbamoylaspartate (tranquillizer). Calcium iron(II) citrate has been used to remedy iron deficiency - it has the advantage of being stable to air oxidation of the iron(II). The cyclamate anion is certainly not therapeutic, but is relevant here. 

The solubility in polyethylene glycol 400 and in aqueous solution of other polyethylene glycols has been described.65-66 The effect of selected surfactants above and below the critical micelle concentration (CMC) on aspirin solubility67 was studied. 

Ethanol must be capable of dissolving aspirin when the solution is hot and aspirin must be less soluble in ethanol when cold. The impurities should be soluble in ethanol. 

Aspirin (acetylsalicylic acid, Figure 7.9) is a derivative of salicyclic acid, which was first used in 1875 as an antipyretic and antirheumatic. The usual dose for mild pain is 300-600 mg orally. In the treatment of rheumatic diseases, larger doses, 5-8 g daily, are often required. Aspirin is rapidly hydrolysed in the plasma, liver and eiythrocytes to salicylate, which is responsible for some, but not all, of the analgesic activity. Both aspirin and salicylate are excreted in the urine. Excretion is facilitated by alkalinisation of the urine. Metabolism is normally very rapid, but the liver enzymes responsible for metabolism are easily saturated and after multiple doses the terminal half-life may increase from the normal 2-3 h to 10 h. A soluble salt, lysine acetylsalicylic acid, with similar pharmacological properties to aspirin, has been used by parenteral administration for postoperative pain. Aspirin in low doses (80-160 mg daily) is widely used in patients with cardiovascular disease to reduce the incidence of myocardial infarction and strokes. The prophylaxis against thromboembolic disease by low-dose aspirin is due to inhibition of COX-1-generated thromboxane A2 production. Because platelets do not form new enzymes, and COX-1 is irreversibly inhibited by aspirin, inhibition of platelet function lasts for the lifetime of a platelet (8-10 days). 

Salicylic acid is a simple organic acid with a pKa of 3.0. Aspirin (acetylsalicylic acid ASA) has a pKa of 3.5 (see Table 1-3). The salicylates are rapidly absorbed from the stomach and upper small intestine yielding a peak plasma salicylate level within 1-2 hours. Aspirin is absorbed as such and is rapidly hydrolyzed (serum half-life 15 minutes) to acetic acid and salicylate by esterases in tissue and blood (Figure 36-3). Salicylate is nonlinearly bound to albumin. Alkalinization of the urine increases the rate of excretion of free salicylate and its water-soluble conjugates. 

A quick means to identify whether or not a drug may be more suitable for solution or suspension is to overlap the pH-stability profile with the pH-solubility profile. This overlap creates a window, which may suggest which dosage form might be most desirable and subsequently the type of excipients needed. The overlapped figures below demonstrate for aspirin (which is a weak acid) that the pH of greatest stability is also the pH at which there is low solubility (Fig. 1). 

Figure 1 pH stability and solubility curves of aspirin. Source From Ref. 3. 

Soluble Aspirin Paint Pigment Ferrous Glutinate Ferrous Succinate Lithium Hydroxide Tungsten Alloy Stabilized Diazamin... 

Albumin is the most abundant protein in human and other animal plasma. It is estimated that up to 40% of the total albumin in humans is in circulation transporting essential nutrients, especially those that are sparingly soluble in aqueous-based plasma. For example, the fatty acids, which are important fuel molecules for the peripheral tissue, are distributed by albumin. In addition, albumin is the plasma transport protein for other substances including bilirubin, thyroxine, and steroid hormones. Also, many drugs including aspirin, sulfanilamides, clofibrate, and digitalis bind to albumin and are most likely carried to their sites of action by the protein. 

Therefore, according to this model, acetylsalicylic acid (aspirin) is best absorbed when the pH of the stomach is highly acidic. This high acidity, however, limits its aqueous solubility. 

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