October 2006722Dipyrone (Optalgin®) is a non-steroidal anti-inflammatory drug that inhibits cyclooxygenase-1 and cyclooxygenase-2 activity, thereby reducing the production of prostaglandin E2 and E1. This effect is not unique to pregnant women or fetuses but occurs widely in adults, particularly in patients with contracted intravascular fluid volume as a result of congestive heart failure, cirrhosis, diuretic use, or restricted sodium intake. All these clinical situations are at increased risk for NSAID-related changes in renal function. The drug is widely used in many countries as an an–algetic and antipyretic agent, especially in some parts of Europe, South America and Asia. It was banned in the United States by the Food and Drug Administration in 1977 because of a possible association with agranulocytosis. In contrast to other NSAIDs, precautions regarding the use of dipyrone during pregnancy are not well defined and information on its safety in pregnancy is scarce. A weak association with Wilms’ tumor was found in children of women who took dipyrone during pregnancy [1]. Other suggested adverse ef–fects are leukemia and neural tube defects found in mice. The association of NSAIDs with oligohydramnios was described in a series of patients who took indometha–cin [2], and in only two case reports of dipyrone use. We report another case of dipyrone-associated oligohydramnios with fetal ductus arteriosus restriction.Patient DescriptionA 26 year old woman in the 35th week of her first pregnancy was admitted with an Escherichia coli urinary tract infection. Her past medical history was uneventful. Her pregnancy was also uneventful, except NSAID = non-steroidal anti-inflammatory drugfor a positive triple test. All sonographic studies during pregnancy were normal, including amniotic fluid evaluated 8 days before admission to the hospital. Three days before her index admission she took dipyrone (Optalgin®, V-Talgin®, Phanalgin®), 6 g a day for 3 days, and papaverine HCL to relieve her urinary symptoms. Her physical examination was normal except for left flank tenderness. She was normotensive. Her kidney func–tion tests were within normal values for pregnant women; urea 3.0 mmol/L (normal non-pregnant values 3.3–6.5 mmol/L), cre–atinine 44 μmol/L (normal non-pregnant 60–106 μmol/L), uric acid 184 μmol/L (normal 150–380 μmol/L). Complete blood count was normal as were blood electrolytes.Obstetric ultrasound examination re–vealed oligohydramnios with an amniotic fluid index of 40 mm (normal 50–240 mm) and restricted ductus arteriosus. Analgesic treatment was replaced with paracetamol, and antibiotic treatment with intravenous cefuroxime was initiated. Serial fetal sonographic examinations showed an im–provement in ductus arteriosus width and in amniotic fluid volume 2 days after di–pyrone cessation, which gradually returned to normal (AFI 140 mm) within 1 week. A normal healthy baby was vaginally born in the 40th week of her pregnancy. CommentWe describe a case of oligohydramnios that might have been caused by dipyrone use. In this case, oligohydramnios and ductus arteriosus narrowing occurred fol–lowing the use of the drug and resolved soon after its discontinuation. This case adds to two previously described cases AFI = amniotic fluid indexand this report is the first to describe narrowing of the ductus arteriosus in such circumstances [3,4]. Catalan et al. [3] reported a case of a term pregnant woman who suffered from renal colic treated with high dose dipyrone and who developed oligohydramnios 60 hours after treatment initiation. Thirty-five hours after dipyrone was discontinued the AFI returned to normal. In the second report, Sanchez-de-la-Nieta and colleagues [4] described a healthy 21 year old woman who developed maternal acute renal failure, rash and oligohydramnios (AFI 20 mm) 10 days after taking dipyrone, 1.5–3 g a day for 10 days, to relieve her back pain. Following treatment with intravenous fluids and dipyrone discontinuation the rash disappeared and blood analyses and the AFI returned to normal (AFI 60 mm). Dipyrone associated with renal failure during pregnancy may be explained by two possible mechanisms: a) reversible renal ischemia secondary to inhibition of prostaglandin synthesis, and b) acute tubulointerstitial nephritis. Both cases, as well as ours, suggest a possible effect of the drug on fetal kidney function, reflected by the reduction in amniotic fluid index. The two previous case reports mention the use of high dose magnesium dipyrone, whereas in our patient the compound used was sodium dipyrone. Cases of agranulocytosis and aplastic anemia were reported with the sodium compound but we are not aware of differences in effect between magnesium and sodium on the ductus arteriousus or fetal kidneys.In all cases described, including the present report, dipyrone withdrawal was associated with a dramatic improvement in the amniotic fluid volume. In these cases, the mechanism of oligohydramnios is probably related to the reduced produc–Dipyro