Analgesics/antipyretics dipyrone

Dipyrone is a water-soluble pyrazolone derivative available in oral, rectal, and injectable forms. It has been recogifized as an effective analgesic, antipyretic, and antispasmodic drug. Some antiinflammatory properties have also been recogifized in pharmacological models, although it is stiU questionable whether this is of any clinical relevance. Dipyrone is indicated in severe pain, particularly, pain associated with smooth-muscle spasm or colic affecting the GI, biliary, or urinary tract. It is also useful in fever that is refractory to other treatment. 

Acetaminophen, the amphiphilic acids acetylsalicylic acid (ASA), ibuprofen, and others, as well as some pyrazolone derivatives, such as aminopyrine and dipyrone, are grouped under the label antipyretic analgesics to distinguish them from opioid analgesics, because they share the ability to reduce fever. 

Antipyretic analgesics represent p-ami-nophenol or pyrazolone derivatives with clinically useful analgesic and antipyretic efficacy. Their mechanism of action is not completely understood but thought to be mediated via inhibition of prostanoid formation by variants of COX enzymes. Acetaminophen (paracetamol), phenazone, and dipyrone belong in this group. 

Drugs like phenazone, aminophenazone (aminopyrine), dipyrone, phenylbutazone, oxyphenbutazone, sulfinpyrazone, ete., belonging to this eategory, besides their antipyretic-analgesic action, have also been reported to exhibit anti-inflammatory properties. These compoimds have been dealt separately in the chapter on antipyretic-analgesics . 

Dipyrone, also known as metamizole sodium. Analgin, Novalgin or Melubrin, displays the highest efiScacy among antipyretic analgesics and is effective in visceral pain associated with smooth muscle spasm. It is rapidly absorbed when administered orally or via the rectal route. It is water soluble and is also available for intravenous administration. Dipyrone is a prodrug which, after oral administration, is rapidly hydrolysed in the gastric environment to its major metabolite 4-methyl-amino-antipyrine (MAA) and... 

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