AimsTo study the population pharmacokinetics of piperaquine after co-administration with dihydroartemisinin in uncomplicated malaria. MethodsThe disposition of piperaquine was studied in 85 Cambodian patients with uncomplicated falciparum or vivax malaria treated with the piperaquine-dihydroartemisinin coformulation Artekin ® . All patients were given Artekin ® orally at 0, 6, 24 and 32 h with a total piperaquine dose of 32-35 mg base kg -1 . Adults were given tablets while children received either tablets or a dispersible granule formulation. Patients underwent either intensive (17-19 samples) or sparse (2-5 samples) blood sampling schedules over 35 days and clinical/parasitological follow-up over > 28 days. Piperaquine in plasma was quantified by high performance liquid chromatography. ResultsAll patients achieved fever clearance within 24 h and parasite clearance within 72 h. The 28-day cure rate was 97% in adults and 98% in children. A covariate-free twocompartment population model with first-order absorption and elimination gave the most robust representation of the plasma concentration-time data in both adults and children. In adults ( n = 38), the median (interquartile range) derived pharmacokinetic descriptors CL/ F , V ss / F and t 1/2,z were 0.9 l h -1 kg -1 (0.79-1.02 l h -1 kg -1 ), 574 l kg -1 (371-711 l kg -1 ) and 23 days (19-28 days), respectively. In children ( n = 47), corresponding values were 1.8 l h(332-1205 l kg -1 ) and 14 days (10-18 days), respectively. ConclusionsPiperaquine is a highly lipid-soluble drug with a large V ss / F , long t 1/2,z and a clearance that is markedly higher in children than in adults.

Critically ill patients exhibit a range of organ dysfunctions and often require treatment with a variety of drugs including sedatives, analgesics, neuromuscular blockers, antimicrobials, inotropes and gastric acid suppressants. Understanding how organ dysfunction can alter the pharmacokinetics of drugs is a vital aspect of therapy in this patient group. Many drugs will need to be given intravenously because of gastrointestinal failure. For those occasions on which the oral route is possible, bioavailability may be altered by hypomotility, changes in gastrointestinal pH and enteral feeding. Hepatic and renal dysfunction are the primary determinants of drug clearance, and hence of steady-state drug concentrations, and of efficacy and toxicity in the individual patient. Oxidative metabolism is the main clearance mechanism for many drugs and there is increasing recognition of the importance of decreased activity of the hepatic cytochrome P450 system in critically ill patients. Renal failure is equally important with both filtration and secretion clearance mechanisms being required for the removal of parent drugs and their active metabolites. Changes in the steady-state volume of distribution are often secondary to renal failure and may lower the effective drug concentrations in the body. Failure of the central nervous system, muscle, the endothelial system and endocrine system may also affect the pharmacokinetics of specific drugs. Time-dependency of alterations in pharmacokinetic parameters is well documented for some drugs. Understanding the underlying pathophysiology in the critically ill and applying pharmacokinetic principles in selection of drug and dose regimen is, therefore, crucial to optimising the pharmacodynamic response and outcome.

Aims To obtain comprehensive pharmacokinetic and pharmacodynamic data for artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) following i.v. and oral administration of ARTS to patients with acute, uncomplicated falciparum malaria. Methods Twenty-six Vietnamese patients with falciparum malaria were randomized to receive either i.v. ARTS (120 mg; group 1) or oral ARTS (100 mg; group 2), with the alternative preparation given 8 h later in an open crossover design. Mefloquine (750 mg) was administered at 24 h. Plasma concentrations of ARTS and DHA were determined by h.p.l.c. assay. Pharmacokinetic parameters were calculated by non-compartmental methods. The time to 50% parasite clearance (PCT 50 ) was calculated by linear interpolation of parasite density determinations. Linear least squares and multiple linear regression analyses were used to evaluate pharmacokineticpharmacodynamic relationships. Results Following i.v. bolus, ARTS had a peak concentration of 29.5 mm (11 mg l −1 ), elimination t 1/2 =2.7 min, CL=2.33 l h −1 kg −1 and V=0.14 l kg −1 .The C max for DHA was 9.3 mm (2.64 mg l . Following oral ARTS, relative bioavailability of DHA was 82%, C max was 2.6 mm (0.74 mg l −1 ), t 1/2 =39 min, and MAT=67 min. Overall, the PCT 50 and fever clearance time (FCT) were 6.5 h and 24 h, respectively. There was no correlation between PCT 50 or FCT and AUC, C max or MRT for DHA. Conclusions Despite rapid clearance of ARTS and DHA in patients with uncomplicated falciparum malaria, prompt parasite and fever clearance were achieved. High relative bioavailability of DHA following oral ARTS administration, and clinical outcomes comparable with those after i.v. ARTS, support the use of the oral formulation in the primary care setting.

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WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Domperidone is an effective treatment for some mothers with insufficient milk supply.• However, dose-effect data are not available, and the safety of domperidone use in both mother and infant has been questioned. WHAT THIS STUDY ADDS• Domperidone only increases milk production in about two-thirds of preterm mothers with insufficient milk supply.• On average, the responders showed increasing levels of milk production with dose escalation from 30 mg to 60 mg daily.• The amount of domperidone that transferred into breast milk was very low, and the risk to the breastfed infant is minimal. AIMSTo investigate the possibility of a dose-response relationship for the use of domperidone in treating insufficient milk supply in mothers of preterm infants, and to quantify the exposure of the breastfed infant to domperidone. METHODSSix preterm mothers received domperidone (30 mg daily or 60 mg daily) in a double-blind, randomized, crossover trial. Milk production and serum prolactin were measured before and during the trial, and domperidone concentration in milk was measured during drug treatment. RESULTSFor milk production, two of the mothers were 'nonresponders' , whereas the other four were 'responders' and showed a significant increase in milk production from 8.7 Ϯ 3.1 g h -1 in the run-in phase (mean Ϯ SEM), 23.6 Ϯ 3.9 g h -1 for the 30-mg dose (P = 0.0217) and 29.4 Ϯ 6.6 g h -1 for the 60-mg dose (P = 0.0047). In all participants, serum prolactin was significantly increased for both doses, but the response was not dose dependent. Median (interquartile range) domperidone concentrations in milk over a dose interval at steady-state were 0.28 mg l -1 (0.24-0.43) and 0.49 mg l -1 (0.33-0.72) for the 30-mg and 60-mg doses, respectively. The mean relative infant dose was 0.012% at 30 mg daily and 0.009% at 60 mg daily. CONCLUSIONIn one-third of mothers, domperidone did not increase milk production. In the remainder, milk production increased at both domperidone doses, and there was a trend for a dose-response relationship. The amount of domperidone that transfers into milk was extremely low, and infant exposure via breastfeeding was not considered to be significant.

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ABSTRACT:The aim of this study was to elucidate the metabolic pathways for dihydroartemisinin (DHA), the active metabolite of the artemisinin derivative artesunate (ARTS). Urine was collected from 17 Vietnamese adults with falciparum malaria who had received 120 mg of ARTS i.v., and metabolites were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS). ) but not with UGT1A1 or UGT1A6. There was no significant metabolism of DHA by cytochrome-P450 oxidation or by cytosolic sulfotransferases. We conclude that ␣-DHA-G is an important metabolite of DHA in humans and that its formation is catalyzed by UGT1A9 and UGT2B7.

The trend globally for mothers to breastfeed has highlighted the need for information on drug transfer into breast milk and the extent to which the suckling neonate may be exposed and affected. This review discusses robust study methodologies that will yield high-quality information on all aspects of this process. Methods for assessing drug transfer into breast milk are examined. The place of the milk/plasma ratio, the amount of drug in breast milk, and the volume of milk produced are discussed in the context of their utility in estimating both absolute and relative infant dose. The measurement of plasma drug concentrations and pharmacodynamic effects in the breastfed infant exposed to drugs are identified as important factors that can assist in deciding whether drug present in breast milk is a significant risk for the nursing infant.