Chloroquine blood concentrations and malaria prophylaxis in Tanzanian women during the second and third trimesters of pregnancy

Systematic Review and Pharmacological Considerations for Chloroquine and Its Analogs in the Treatment for COVID-19

COVID-19 has been announced pandemic by WHO and over 17,000,000 people infected (Till April 21st 2020). The disease is currently under control in China, with a curative rate of 86.8%. Chloroquine (CQ) is an old anti-malarial drug with good tolerability, which had proved to be effective in previous SARS-coronavirus, which spread and disappeared between 2002-2003. In vitro studies demonstrated the efficacy of CQ in curing COVID-19. Consequently, via analytical PBPK modeling, a further preliminary clinical trial has proved the efficacy and safety of CQ in China., and multiple clinical trials were registered and approved to investigate the activity of other analogs of CQ against COVID-19. We have listed all the clinical trials and made a meta-analysis of published data of hydroxychloroquine (HCQ). HCQ could increase the CT improvement and adverse reactions (ADRs) significantly though there was considerable heterogeneity among current researches. Actually, CQ and its analogs have unique pharmacokinetic characteristics, which would induce severe side effects in some circumstances. We have then summarized pharmacological considerations for these drugs so as to provide to the busy clinicians to avoid potential side effects when administered CQ or its analogs to COVID-19 patients, especially in the elderly, pediatrics, and pregnancies.

Updated pharmacokinetic considerations for the use of antimalarial drugs in pregnant women

INTRODUCTION

The association between pregnancy and altered drug pharmacokinetic (PK) properties is acknowledged, as is its impact on drug plasma concentrations and thus therapeutic efficacy. However, there have been few robust PK studies of antimalarial use in pregnancy. Given that inadequate dosing for prevention or treatment of malaria in pregnancy can result in negative maternal/infant outcomes, along with the potential to select for parasite drug resistance, it is imperative that reliable pregnancy-specific dosing recommendations are established.

AREAS COVERED

PK studies of antimalarial drugs in pregnancy. The present review summarizes the efficacy and PK properties of WHO-recommended therapies used in pregnancy, with a focus on PK studies published since 2014.

EXPERT OPINION

Changes in antimalarial drug disposition in pregnancy are well described, yet pregnant women continue to receive treatment regimens optimized for non-pregnant adults. Contemporary in silico modeling has recently identified a series of alternative dosing regimens that are predicted to provide optimal therapeutic efficacy for pregnant women.

Drug dosing during pregnancy-opportunities for physiologically based pharmacokinetic models

Drugs can have harmful effects on the embryo or the fetus at any point during pregnancy. Not all the damaging effects of intrauterine exposure to drugs are obvious at birth, some may only manifest later in life. Thus, drugs should be prescribed in pregnancy only if the expected benefit to the mother is thought to be greater than the risk to the fetus. Dosing of drugs during pregnancy is often empirically determined and based upon evidence from studies of non-pregnant subjects, which may lead to suboptimal dosing, particularly during the third trimester. This review collates examples of drugs with known recommendations for dose adjustment during pregnancy, in addition to providing an example of the potential use of PBPK models in dose adjustment recommendation during pregnancy within the context of drug-drug interactions. For many drugs, such as antidepressants and antiretroviral drugs, dose adjustment has been recommended based on pharmacokinetic studies demonstrating a reduction in drug concentrations. However, there is relatively limited (and sometimes inconsistent) information regarding the clinical impact of these pharmacokinetic changes during pregnancy and the effect of subsequent dose adjustments. Examples of using pregnancy PBPK models to predict feto-maternal drug exposures and their applications to facilitate and guide dose assessment throughout gestation are discussed.

Treatment of uncomplicated and severe malaria during pregnancy

Over the past 10 years, the available evidence on the treatment of malaria during pregnancy has increased substantially. Owing to their relative ease of use, good sensitivity and specificity, histidine rich protein 2 based rapid diagnostic tests are appropriate for symptomatic pregnant women; however, such tests are less appropriate for systematic screening because they will not detect an important proportion of infections among asymptomatic women. The effect of pregnancy on the pharmacokinetics of antimalarial drugs varies greatly between studies and class of antimalarial drugs, emphasising the need for prospective studies in pregnant and non-pregnant women. For the treatment of malaria during the first trimester, international guidelines are being reviewed by WHO. For the second and third trimester of pregnancy, results from several trials have confirmed that artemisinin-based combination treatments are safe and efficacious, although tolerability and efficacy might vary by treatment. It is now essential to translate such evidence into policies and clinical practice that benefit pregnant women in countries where malaria is endemic. Access to parasitological diagnosis or appropriate antimalarial treatment remains low in many countries and regions. Therefore, there is a pressing need for research to identify quality improvement interventions targeting pregnant women and health providers. In addition, efficient and practical systems for pharmacovigilance are needed to further expand knowledge on the safety of antimalarial drugs, particularly in the first trimester of pregnancy.

Optimal antimalarial dose regimens for chloroquine in pregnancy based on population pharmacokinetic modelling

Despite extensive use and accumulated evidence of safety, there have been few pharmacokinetic studies from which appropriate chloroquine (CQ) dosing regimens could be developed specifically for pregnant women. Such optimised CQ-based regimens, used as treatment for acute malaria or as intermittent preventive treatment in pregnancy (IPTp), may have a valuable role if parasite CQ sensitivity returns following reduced drug pressure. In this study, population pharmacokinetic/pharmacodynamic modelling was used to simultaneously analyse plasma concentration-time data for CQ and its active metabolite desethylchloroquine (DCQ) in 44 non-pregnant and 45 pregnant Papua New Guinean women treated with CQ and sulfadoxine/pyrimethamine or azithromycin (AZM). Pregnancy was associated with 16% and 49% increases in CQ and DCQ clearance, respectively, as well as a 24% reduction in CQ relative bioavailability. Clearance of DCQ was 22% lower in those who received AZM in both groups. Simulations based on the final multicompartmental model demonstrated that a 33% CQ dose increase may be suitable for acute treatment for malaria in pregnancy as it resulted in equivalent exposure to that in non-pregnant women receiving recommended doses, whilst a double dose would likely be required for an effective duration of post-treatment prophylaxis when used as IPTp especially in areas of CQ resistance. The impact of co-administered AZM was clinically insignificant in simulations. The results of past/ongoing trials employing recommended adult doses of CQ-based regimens in pregnant women should be interpreted in light of these findings, and consideration should be given to using increased doses in future trials.

Pregnancy-Associated Changes in Pharmacokinetics: A Systematic Review

BACKGROUND

Women are commonly prescribed a variety of medications during pregnancy. As most organ systems are affected by the substantial anatomical and physiological changes that occur during pregnancy, it is expected that pharmacokinetics (PK) (absorption, distribution, metabolism, and excretion of drugs) would also be affected in ways that may necessitate changes in dosing schedules. The objective of this study was to systematically identify existing clinically relevant evidence on PK changes during pregnancy.

METHODS AND FINDINGS

Systematic searches were conducted in MEDLINE (Ovid), Embase (Ovid), Cochrane Central Register of Controlled Trials (Ovid), and Web of Science (Thomson Reuters), from database inception to August 31, 2015. An update of the search from September 1, 2015, to May 20, 2016, was performed, and relevant data were added to the present review. No language or date restrictions were applied. All publications of clinical PK studies involving a group of pregnant women with a comparison to nonpregnant participants or nonpregnant population data were eligible to be included in this review. A total of 198 studies involving 121 different medications fulfilled the inclusion criteria. In these studies, commonly investigated drug classes included antiretrovirals (54 studies), antiepileptic drugs (27 studies), antibiotics (23 studies), antimalarial drugs (22 studies), and cardiovascular drugs (17 studies). Overall, pregnancy-associated changes in PK parameters were often observed as consistent findings among many studies, particularly enhanced drug elimination and decreased exposure to total drugs (bound and unbound to plasma proteins) at a given dose. However, associated alterations in clinical responses and outcomes, or lack thereof, remain largely unknown.

CONCLUSION

This systematic review of pregnancy-associated PK changes identifies a significant gap between the accumulating knowledge of PK changes in pregnant women and our understanding of their clinical impact for both mother and fetus. It is essential for clinicians to be aware of these unique pregnancy-related changes in PK, and to critically examine their clinical implications.

Pharmacokinetics of antimalarials in pregnancy: a systematic review

Malaria is a serious parasitic infection, which affects millions of people worldwide. As pregnancy has been shown to alter the pharmacokinetics of many medications, the efficacy and safety of antimalarial drug regimens may be compromised in pregnant women. The objective of this review is to systematically review published literature on the pharmacokinetics of antimalarial agents in pregnant women. A search of MEDLINE (1948-May 2011), EMBASE (1980-May 2011), International Pharmaceutical Abstracts (1970-May 2011), Google and Google Scholar was conducted for articles describing the pharmacokinetics of antimalarials in pregnancy (and supplemented by a bibliographic review of all relevant articles); all identified studies were summarized and evaluated according to the level of evidence, based on the classification system developed by the US Preventive Services Task Force. Identified articles were included in the review if the study had at least one group that reported at least one pharmacokinetic parameter of interest in pregnant women. Articles were excluded from the review if no pharmacokinetic information was reported or if both pregnant and non-pregnant women were analysed within the same group. For quinine and its metabolites, there were three articles (one level II-1 and two level III); for artemisinin compounds, two articles (both level III); for lumefantrine, two articles (both level III); for atovaquone, two articles (both level III); for proguanil, three articles (one level II-1 and two level III); for sulfadoxine, three articles (all level II-1); for pyrimethamine, three articles (all level II-1); for chloroquine and its metabolite, four articles (three level II-1 and one level II-3); for mefloquine, two articles (one level II-1 and one level III); and for azithromycin, two articles (one level II-1 and one level III). Although comparative trials were identified, most of these studies were descriptive and classified as level III evidence. The main findings showed that pharmacokinetic parameters are commonly altered in pregnancy for the majority of recommended agents. Importantly, first-line regimens of artemisinin-based compounds, lumefantrine, chloroquine and pyrimethamine/sulfadoxine may undergo significant changes that could decrease therapeutic efficacy. These changes are usually due to increases in the apparent oral clearance and volume of distribution that commonly occur in pregnant women, and may result in decreased exposure and increased therapeutic failure. In order to assess the clinical implications of these changes and to provide safe and effective dosage regimens, there is an immediate need for dose-optimization studies of all recommended first- and second-line agents used in pregnant women with malaria.

Pharmacokinetics of amodiaquine and desethylamodiaquine in pregnant and postpartum women with Plasmodium vivax malaria

In order to study the pharmacokinetic properties of amodiaquine and desethylamodiaquine during pregnancy, 24 pregnant women in the second and third trimesters of pregnancy and with Plasmodium vivax malaria were treated with amodiaquine (10 mg/kg of body weight/day) for 3 days. The same women were studied again at 3 months postpartum. Plasma was analyzed for amodiaquine and desethylamodiaquine by use of a liquid chromatography-tandem mass spectrometry method. Individual concentration-time data were evaluated using noncompartmental analysis. There were no clinically relevant differences in the pharmacokinetics of amodiaquine and desethylamodiaquine between pregnant (n = 24) and postpartum (n = 18) women. The results suggest that the current amodiaquine dosing regimen is adequate for the treatment of P. vivax infections during pregnancy.

Prevention and treatment of malaria in pregnancy

Malaria in pregnancy is a substantial public health issue in many tropical countries. However, its prevention and treatment have been hindered because of fears of adverse drug effects in pregnant women recruited to intervention studies. This article details the pharmacological agents and management strategies currently or potentially available for use in pregnant women with or at risk of malaria. There are deficiencies in pharmacokinetic, tolerability, safety and efficacy data for even well-established drugs and combinations. This can have serious implications for the design of rational dose regimens. Approaches such as intermittent preventive treatment are increasingly employed in endemic areas with proven benefits, but the emergence of parasite drug resistance means that new strategies and drug regimens should be continually evaluated.

Pharmacokinetics of chloroquine and monodesethylchloroquine in pregnancy

In order to determine the pharmacokinetic disposition of chloroquine (CQ) and its active metabolite, desethylchloroquine (DECQ), when administered as intermittent presumptive treatment in pregnancy (IPTp) for malaria, 30 Papua New Guinean women in the second or third trimester of pregnancy and 30 age-matched nonpregnant women were administered three daily doses of 450 mg CQ (8.5 mg/kg of body weight/day) in addition to a single dose of sulfadoxine-pyrimethamine. For all women, blood was taken at baseline; at 1, 2, 4, 6, 12, 18, 24, 30, 48, and 72 h posttreatment; and at 7, 10, 14, 28, and 42 days posttreatment. Plasma was subsequently assayed for CQ and DECQ by high-performance liquid chromatography, and population pharmacokinetic modeling was performed. Pregnant subjects had significantly lower area under the plasma concentration-time curve for both CQ (35,750 versus 47,892 microg.h/liter, P < 0.001) and DECQ (23,073 versus 41,584 microg.h/liter, P < 0.001), reflecting significant differences in elimination half-lives and in volumes of distribution and clearances relative to bioavailability. Reduced plasma concentrations of both CQ and DECQ could compromise both curative efficacy and posttreatment prophylactic properties in pregnant patients. Higher IPTp CQ doses may be desirable but could increase the risk of adverse hemodynamic effects.

Severe embryotoxicity of artemisinin derivatives in experimental animals, but possibly safe in pregnant women

Preclinical studies in rodents have demonstrated that artemisinins, especially injectable artesunate, can induce fetal death and congenital malformations at a low dose range. The embryotoxicity can be induced in those animals only within a narrow window in early embryogenesis. Evidence was presented that the mechanism by which embryotoxicity of artemisinins occurs seems to be limited to fetal erythropoiesis and vasculogenesis/ angiogenesis on the very earliest developing red blood cells, causing severe anemia in the embryos with higher drug peak concentrations. However, this embryotoxicity has not been convincingly observed in clinical trials from 1,837 pregnant women, including 176 patients in the first trimester exposed to an artemisinin agent or artemisinin-based combination therapy (ACT) from 1989 to 2009. In the rodent, the sensitive early red cells are produced synchronously over one day with single or multiple exposures to the drug can result in a high proportion of cell deaths. In contrast, primates required a longer period of treatment of 12 days to induce such embryonic loss. In humans only limited information is available about this stage of red cell development; however, it is known to take place over a longer time period, and it may well be that a limited period of treatment of 2 to 3 days for malaria would not produce serious toxic effects. In addition, current oral intake, the most commonly used route of administration in pregnant women with an ACT, results in lower peak concentration and shorter exposure time of artemisinins that demonstrated that such a concentration–course profile is unlikely to induce the embryotoxicity. When relating the animal and human toxicity of artemisinins, the different drug sensitive period and pharmacokinetic profiles as reviewed in the present report may provide a great margin of safety in the pregnant women.

Treating malaria in pregnancy in developing countries: priorities in clinical research and drug development

Reducing the burden of falciparum malaria in pregnancy is an urgent international public health priority but one that involves considerable challenges. The rapidly declining effectiveness of agents known to be safe in pregnancy, and the limited efficacy, safety and pharmacokinetic data available for many other antimalarial drugs, mean that current options for the treatment of both severe and uncomplicated falciparum malaria in pregnancy are limited. This report summarizes the literature on this subject and recommends drug combinations for evaluation in Phase II/III treatment trials in pregnancy.

Antimalarial drugs and pregnancy: safety, pharmacokinetics, and pharmacovigilance

Before a recommendation for antimalarial drug use in pregnancy is made, it is essential that we understand the potential risks involved and have mechanisms in place to monitor risk during treatment. This requires data on drug disposition during pregnancy and potential toxicological liabilities to the developing fetus and mother. In most cases this information is not available. We review the reproductive toxicology of the main antimalarial drug classes in use or under development. Preclinical data are presented if appropriate, but as human experience overrides such data, in instances in which preclinical studies do not correlate with the human experience the data are reviewed only briefly. Additionally, we highlight the lack of appropriate drug disposition data in pregnancy and suggest mechanisms that can be used to capture data on risk after drug treatment in pregnancy.

The pregnant wilderness traveler

BACKGROUND

Travel during pregnancy, especially, when it involves potentially hazardous activities in remote areas, often raises serious concerns regarding the health and safety risks involved.

METHOD

The authors have researched the available medical literature to identify these risks and present the current recommendations for their prevention and treatment.

RESULTS

Topics addressed include some political and social issues, insurance, basic comfort measures, complications of pregnancy, infectious diseases, environmental exposures, and trauma. Preventive measures include pre-travel evaluation and teaching, possible modifications of the itinerary, vaccinations and medications. Also briefly discussed are the handling of obstetrical emergencies in the field and medical evacuation of the pregnant patient.

CONCLUSIONS

The authors conclude that many trips of this nature can be made relatively safe for the pregnant traveler, but she may need to accept some precautions and modifications of the itinerary that might not otherwise be necessary.

Malaria and the pregnant traveller

Malaria in pregnancy contributes to significant maternal and foetal mortality and morbidity in women in the tropics. Adverse effects for non-immune travellers are potentially devastating for mother and foetus. Women travellers should always be strongly advised against visiting malarious areas if they are pregnant or intend to get pregnant. Chemoprophylactic and treatment options for pregnant women (or those planning to conceive) are extremely limited and lag behind what can currently be offered to non-pregnant travellers. This is because of spread of multi-resistant strains of P. falciparum. Personal protection from malaria vectors remains essential. Mosquito-net and skin repellents (DEET (20%)) are effective. Diagnosis of malaria in travellers is difficult and is more likely to be missed in pregnant travellers due to lower parasitaemia. Pregnant women can succumb rapidly to severe malaria. Should the returned traveller survive an episode of malaria in pregnancy and go on to deliver, the adverse effects on the infant are potentially irreversible. These risks need to be clearly communicated.

Evidence for increased metabolism of chloroquine during the early third trimester of human pregnancy

OBJECTIVE

To examine the possibility of a different extent of chloroquine (CQ) metabolism in human pregnancy by determining blood level profiles of the drug and its major metabolite, desethylchloroquine (CQM).

METHODS

Five women in the early third trimester of pregnancy and five non-pregnant women received each a single 600 mg oral dose of CQ and blood samples were collected at pre-determined intervals following drug administration. Plasma concentrations of CQ and CQM were analysed by an established HPLC method.

RESULTS

The C(max) and AUC(0-48 h) of CQM were significantly higher in the pregnant than the non-pregnant group (P = 0.009). The ratio AUC(CQ)/AUC(CQM) ranged from 0.09 to 0.35 among pregnant women, and from 1.70 to 4.81 among non-pregnant women.

CONCLUSION

Results from this preliminary study indicate an occurrence of induction of metabolism of CQ in the early third trimester of pregnancy. In view of toxicological importance of CQ metabolites, it is suggested that caution should be exercised in evaluation of higher dosage regimen of CQ in pregnant women.

Chloroquine inhibits arginine vasopressin production in isolated rat inner medullary segments induced cAMP collecting duct

Previous studies showed that acute chloroquine administration increases plasma arginine vasopressin (AVP) concentration in the rat without influencing urine flow rate. The present study was designed to investigate whether chloroquine inhibits the AVP-induced cAMP production that mediates the antidiuretic effects of vasopressin. Single inner medullary collecting duct (IMCD) segments were pre-incubated at 35 degrees C for 10 min followed by 4 min at 37 degrees C with combinations of AVP and/or chloroquine with 1 mM 3-isobutyl-I-methylxanthine (IBMX) and cAMP concentrations were measured by radioimmunoassay. To establish the possible site of interference in cAMP production IMCD segments were incubated in the presence of chloroquine and forskolin. Chloroquine at concentrations ranging from 10(-9) M to 10(-6) M did not affect cAMP production by comparison with control. However, AVP (10(-8) M) and forskolin (10(-6) M) significantly (p < 0.01) increased cAMP accumulation. Chloroquine at all concentrations significantly suppressed the AVP stimulated cAMP production (e.g., chloroquine (10(-8) M) + AVP (10(-8) M) 41 +/- 12 fmol/4 mm (n = 9 tubules) vs. AVP (10(-8) M) alone 82 +/- 9 fmol/4 min/mm (n = 37 tubules). Chloroquine at all concentrations tested did not have any effect an forskolin-induced cAMP production. The data suggest that chloroquine inhibits the AVP induced cAMP production at the level of hormone/receptor complex. This possibly explains the previously reported lack of the normal antidiuretic responses of AVP in rats following chloroquine administration.