Promethazine Pethidine

A 2-month-old boy had a cardiac arrest when he was given a combination of pethidine, promethazine, and chlorpromazine in 10 times the recommended dose by the wrong route (intravenously rather than intramuscularly). Within seconds he became apneic and stiff. Cardiopulmonary resuscitation was instituted, including two intravenous doses of adrenaline 0.06 mg and naloxone 0.6 mg, with recovery 7 minutes after the incident and complete resolution 24 hours later. 

FIGURE 1.32 Extraction-time profiles for promethazine (A), methadone (B), amphetamine (C), pethidine (D), and haloperidol (E) in 1 mL sample volume with 0, 5, and 50% methanol added to plasma sample.155 (Reproduced with permission from the Royal Society of Chemistry.)... 

Cefoperazone Sodium Admixture of cefoperazone sodium and aminoglycosides leads to inactivation of these drugs. Cefoperazone sodium is not compatible with other drugs that include diltiazem, pentamidine, perphenazine, pethidine, and promethazine.2... 

The pharmacokinetics and effects of various systemically administered analgesics on the uterus, fetus, and neonate have been reviewed (SED-11, 137). Fetal bradycardia lasting up to 7 minutes was reported in 53 of 1910 fetuses (2.7%) after the administration of pethidine (meperidine) 75 mg and promethazine 25 mg intravenously to the mothers during labor (SED-11,137) (95). 

Pethidine 50 mg plus promethazine 25 mg given intravenously to 14 mothers in labor caused a significant change in fetal heart rate indices 40 minutes after administration (18). There were significant changes in fetal heart rate acceleration of at least 10 beats/minute, acceleration of at least 15 beats/minute, time spent in episodes of high variation, and short-term variation. 

Chlorpromazine has been reported to increase the analgesic effect of pethidine, but increased respiratory depression, sedation, CNS toxicity and hypotension can also occur. Other phenothiazines such as levomepromazine, promethazine, prochlorperazine, pro-piomazine and thioridazine may also interact with pethidine to cause some of these effects. Additive CNS depressant effects would be expected when opioids are given with phenothiazines. 

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