HYPERAMYLASEMIA IN RESPONSE TO RITODRINE OR EPHEDRINE ADMINISTERED TOPREGNANT-WOMEN

BACKGROUND: Ritodrine and ephedrine can induce hyperamylasemia in preg nant women. The incidence of these beta-agonist-induced hyperamylasemi as and their interaction on serum amylase activity are not known. STUD Y DESIGN: Serum amylase activity was determined 12 to 24 hours after t he administration of ritodrine alone (n=140), ephedrine alone (n=160), ephedrine and ritodrine simultaneously (n=34), and ephedrine after pr olonged (greater than or equal to 7 days) use of ritodrine (n=101). RE SULTS: A significantly higher incidence of hyperamylasemia (amylase >2 15 IU/L) was seen in a group treated with ritodrine alone (60/140, 43 percent), ephedrine alone (54/160, 34 percent), or ephedrine plus rito drine (24/34, 71 percent) compared with untreated pregnant women (21/4 26, 4.9 percent). There was no difference in the incidence of of peram ylasemia among the untreated pregnant women and women who received eph edrine after long-term ritodrine (8/101, 7.9 percent). Isozyme pattern s, examined in 72 out of the 146 women with hyperamylasemia after such medications, indicated that salivary-type amylase exclusively was hyp ersecreted. CONCLUSIONS: Clinical doses of beta-agonists such as ephed rine or ritodrine induce hypersecretion of salivary-type amylase in ap proximately one-third of women who are pregnant. Desensitization to be ta-agonists may occur after prolonged use of ritodrine.