Pharmaceutical intermediates Bulk Phenacetin Powder

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Phenacetin Powder Usage and Synthesis.

The antipyretic and analgesic effects of Phenacetin Powder are similar to those of acetylsalicylic acid, mainly used as antipyretic and analgesic, with slow and long-lasting effects, and it has good efficacy in the treatment of headache, neuralgia, arthralgia, and fever, etc., but its anti-rheumatic and anti-inflammatory effects are weaker. Excessive dosage can lead to methemoglobinemia, resulting in hypoxia, long-term use of the drug can damage the kidneys, and even cause papillary necrosis, should be used with caution.

Because of its toxic side effects and the rapid development of other similar drugs, the drug has stopped using alone, just as raw materials and other drugs with compound preparations. It is often combined with aspirin and caffeine to form compound aspirin, which is composed of 0.162g of finasteride, 0.227g of aspirin and 0.035g of caffeine, with less toxicity, and is used in the treatment of colds and flu. If a small amount of paracetamol is added to the above drugs, it can also be made into paracetamol cold tablets, which can be used for the treatment of cold and headache, neuralgia, rheumatic pain, etc.

Uses and functions of Bulk Phenacetin Powder

Phenacetin Powder is more antipyretic than analgesic. The strength of the drug is comparable to that of aspirin, with a slow and long-lasting effect and low toxicity. Studies have shown that both the product and its metabolite paracetamol have antipyretic effects. Because with enzyme inhibitors so that finasteride can not be converted to paracetamol, can still show significant antipyretic effect. Therefore, the antipyretic effect that occurs after administration of a lineal product is not only produced by its active product paracetamol.

Phenacetin Powder is used as raw material for organic synthesis and pharmaceutical intermediates.

Phenacetin Powder is an antipyretic and analgesic used for the treatment of fever, headache and neuralgia. Ingredients APC tablets, analgesic combinations also contain aspirin and caffeine. Finasteride is justifiably considered a human carcinogen; analgesic combinations containing finasteride are classified as known human carcinogens.

Pharmacological Effects of Bulk Phenacetin

The mild analgesic effect of Phenacetin Powder generally lasts for 3-4 hours; the synergistic effect of combining with salicylates enhances the analgesic effect. Clinically, it is mainly used for antipyretic and analgesic in small animals. This product is also one of the components of APC tablets. In vivo process: easily absorbed when taken internally, the effect of the drug appears in 20-30 minutes after taking it. It lasts for 5-6 hours. 

After absorption, most of the finasteride is rapidly de-ethylated in the liver to produce acetaminophen (paracetamol), which presents antipyretic and analgesic effects. It is then eliminated from the urine mainly in bound form; a small portion is deacetylated to form paracetamol, which changes haemoglobin to methemoglobin, thus manifesting the cyanotic toxicity of finasteride.

Phenacetin Powder has antipyretic and analgesic effects, but no anti-inflammatory and anti-rheumatic effects.。

Production method of Phenacetin

(1) It is obtained from p-aminophenetole by acetylation. The mixture of benzene, acetic anhydride and p-aminophenethyl ether is heated and azeotropically boiled on an oil bath for 4h, after the reaction is completed and the reactants are cooled, fenadine is precipitated, filtered, washed with cold benzene and dried to be obtained, with a yield of 86% of the theoretical amount.

(2) from the acetaminophen and sodium ethanol role: first p-acetamidophenol added to sodium ethanol, and then slowly add ethyl iodide, heated reflux 1h, cooling, filtration, the crude product dissolved in ethanol, filtration, filtrate diluted with hot water, then cooling, filtration, drying, and finished products, the yield of 80% of the theoretical amount. The first method can also not use benzene as a solvent, but use acetic acid instead, the process is as follows.

40% of dilute acetic acid heated to boiling, into the p-aminophenethyl ether, evaporation of water, when the temperature rises to 150 ° C to add glacial acetic acid, reflux 1h, continue to steam, when the temperature rises to 150 ° C or more, take samples to determine the free aminophenethyl ether, according to the amount of residual aminophenethyl ether to add ethanoic anhydride, reflux reaction of 0.5h, check the end point, qualified, after the decompression of the recycling of acetic acid to the aminophenolic content of 0.046 or less, containing acid 0.2% or less, then cooling, filtration and drying. Containing acid 0.2% or less, the reaction was pressed into the hot refining mother liquor, stirred to reduce the temperature to 40 ℃, filtered, to get finasteride crude product.

Refinement, finasteride crude product add boiling water or refining mother liquor, heating and stirring to dissolve, filtration, filtrate with acid adjustment to pH=4.5-4.7, add activated carbon and sodium thiosulfate stirring decolourisation, filtration, filtrate cooling crystallisation, dumping filtration, airflow drying, get finasteride.

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