Literature Watch
Metamizole [Dipyrone]
2024 Jun 2. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012–.
ABSTRACT
Metamizole, also known as dipyrone, is an oral analgesic that is not available in the United States but is available over-the-counter in many countries of the world. Therapy with metamizole has been associated with rare severe bone marrow and liver adverse events including agranulocytosis, acute hepatitis, and acute liver failure.
Dabrafenib Therapy and <em>BRAF</em> Genotype
2017 Aug 15 [updated 2023 Dec 4]. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012–.
ABSTRACT
Dabrafenib (brand name Tafinlar) is a kinase inhibitor used in the treatment of individuals with unresectable or metastatic melanoma, metastatic non-small cell lung cancer (NSCLC), locally advanced or metastatic anaplastic thyroid cancer (ATC), pediatric low-grade glioma (LGG), and other unresectable or metastatic solid tumors with specific BRAF variants. Dabrafenib can be used as a single agent to treat melanoma with the BRAF valine 600 to glutamic acid (V600E) variant or in combination with the MEK inhibitor trametinib to treat multiple tumor types with BRAF V600E or V600K variants. (1)
The BRAF protein is an intracellular kinase in the mitogen-activated protein kinases (MAPK) pathway. Functionally, BRAF regulates essential cell processes such as cell growth, division, differentiation, and apoptosis. The gene BRAF is also a proto-oncogene—when mutated, it transforms normal cells into cancerous cells.
Variation in the kinase domain of BRAF is associated with various cancers. The most common BRAF variant, V600E, constitutively activates the kinase and causes cell proliferation in the absence of growth factors that would usually be needed. The V600E variant is detected in approximately 50% of melanomas, 25% of ATC, 2% of NSCLC, and 20% of pediatric LGGs (2, 3, 4, 5, 6, 7, 8).
The FDA-approved label for dabrafenib states that the presence of BRAF mutation in tumor specimens (V600E for dabrafenib monotherapy; V600E or V600K for dabrafenib plus trametinib) should be confirmed using an FDA-approved test before starting treatment with dabrafenib. Dabrafenib is not indicated for the treatment of individuals with wild-type BRAF tumors, or the treatment of colorectal cancer due to intrinsic resistance to BRAF inhibitor monotherapy. (1)
The label also states that individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency should be monitored for signs of hemolytic anemia while taking dabrafenib (1). However, it is important to note that an independent literature review by the Clinical Pharmacogenetics Implementation Consortium found no publications to support or refute this risk and thus issued no guidance for G6PD deficiency and dabrafenib therapy (9).
Atazanavir Therapy and <em>UGT1A1</em> Genotype
2023 Oct 17. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012–.
ABSTRACT
Atazanavir is indicated for managing human immunodeficiency virus (HIV) infection as part of a multi-drug regimen (1). While it was once widely recommended as a first-line therapy, it is now primarily suggested as a second-line therapeutic option due to potential adverse effects leading to discontinuation of therapy (2, 3). Atazanavir can cause hyperbilirubinemia (not associated with liver injury) leading to jaundice, which is a common cause of drug discontinuation. Individuals with 2 decreased-function alleles for UGT1A1 are most likely to experience jaundice leading to atazanavir discontinuation, although this can occur despite the individual having a reference UGT1A1 genotype (4). The Clinical Pharmacogenetics Implementation Consortium (CPIC) recommends that when an individual is a known UGT1A1 poor metabolizer, an alternative therapy should be considered particularly when jaundice is of concern to the individual (Table 1) (4). The US Food and Drug Administration (FDA) approved drug label states that certain comedications that depend upon UGT1A1 or the cytochrome P450 family member CYP3A are contraindications for atazanavir therapy due to the potential for elevated plasma concentrations of these comedications (1).
Siponimod Therapy and <em>CYP2C9</em> Genotype
2023 Aug 9. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012–.
ABSTRACT
Siponimod (brand name Mayzent) is a sphingosine-1-phosphate (S1P) receptor modulator used in the treatment and management of relapsing forms of multiple sclerosis (MS) in adults. It works by targeting lymphocytes to decrease the number of circulating cells that are associated with MS symptomatic attacks and disease progression and may also have a direct neuroprotective impact. Siponimod strongly binds to the S1P type 1 and type 5 receptors that are abundantly expressed on lymphocytes and multiple other cell types in the central nervous system (CNS). Off-target interactions and effects on cardiac cells may occur, also. The use of a dose titration schedule is recommended to decrease the risk of bradycardia (see Table 1, Table 2) (1, 2). This medication is approved for multiple forms of relapsing MS (RMS) in the United States (1) and for active, secondary progressive disease in Europe and Canada (2, 3).
Siponimod is metabolized by members of the cytochrome P450 family, specifically CYP2C9 and, to a lesser extent CYP3A4. The CYP2C9 gene is polymorphic and activity scores are used to categorize diplotype into phenotype. Decreased CYP2C9 metabolic activity is associated with increased exposure to siponimod and increased risk of adverse effects. Therefore, individuals with the CYP2C9*3/*3 diplotype (activity score = 0) are contraindicated from taking siponimod (1, 2). Individuals with one copy of the no-function *3 allele (diplotype with activity scores of 0.5 or 1.0) are advised to take half the standard maintenance dose (1, 2). Consideration of genotype and activity score is essential for CYP2C9-based siponimod dosing because labeled dose recommendations are not categorized by phenotype. In the US, there is a modified titration schedule for individuals with a CYP2C9*3 allele (Table 1)(1); however, the European prescribing guidelines do not modify the titration schedule for individuals with a single copy of the CYP2C9*3 allele (heterozygous for CYP2C9*3) (Table 2) (2). The Dutch Pharmacogenetics Working Group (DPWG) of the Royal Dutch Association for the Advancement of Pharmacy similarly recommends a 50% reduced maintenance dosage for intermediate metabolizers (IM) (Table 3) (4). It should be noted that dose recommendations in the Siponimod package label are limited to diplotypes consisting of only CYP2C9 *1,*2, and *3 alleles due to lack of clinical data on the impact of other decreased or no-function alleles(1), while other medication and testing guidelines also consider*5, *6, *8, and *11 (5, 6).
Belinostat Therapy and <em>UGT1A1</em> Genotype
2023 Jul 20. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012–.
ABSTRACT
Belinostat (brand name Beleodaq) is a histone deacetylase (HDAC) inhibitor, approved for the treatment of relapsed or refractory peripheral T-cell lymphomas (PTCLs) (1). Belinostat targets 3 classes of HDACs (I, II and IV), resulting in higher levels of acetylation of both histone and non-histone proteins, thus reversing the changes in protein acetylation that are frequently disrupted during oncogenesis. Belinostat is administered as an infusion at a rate of 1000 mg/m2 for 30 minutes on days 1–5 of a 21-day cycle (1).
Belinostat has a relatively short half-life and is primarily metabolized by uridine diphosphate (UDP)-glucuronosyltransferase 1A1 (UGT1A1)-mediated glucuronidation, with minor contributions from other UGT and cytochrome P450 (CYP) enzymes (1, 2). Genetic variation at the UGT1A1 locus can result in decreased enzyme activity and thus increased exposure to belinostat. The US Food and Drug Administration (FDA)-approved drug label recommends a 25% decrease in dose for individuals who are known to be homozygous for the UGT1A1*28 reduced function allele (Table 1) (1). Additional indications for dose reduction include grade 3 or 4 adverse reactions or significant decrease in neutrophil or platelet counts following belinostat administration (1). Some studies have suggested that other variant alleles may also lead to increased belinostat exposure, such as UGT1A1*60; however, no specific recommendations for dose reduction have been made for these alleles by either the FDA or other professional pharmacogenetic consortia. Belinostat should not be administered with other medications that can inhibit UGT1A1 function (1), such as nilotinib, ketoconazole, or ripretinib.
Primaquine Therapy and <em>G6PD</em> and <em>CYP2D6</em> Genotype
2023 Jul 6. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012–.
ABSTRACT
Primaquine is a potent antimalarial medication indicated for the radical cure of malaria caused by Plasmodium vivax (P. vivax) and Plasmodium ovale (P. ovale) species (1, 2). Malaria is a blood borne infection caused by infection of Plasmodium parasites that is spread by mosquitos. The P. vivax and P. ovale species present a particular challenge to treat because the parasitic life cycle includes a dormant, liver-specific stage that is not susceptible to other antimalarial medications. Thus, primaquine is often used with other therapies such as chloroquine or artemisinin-based medicines that target the reproductive, active forms of the parasite. Primaquine is also used to prevent transmission of malaria caused by Plasmodium falciparum (P. falciparum) species. A single, low dose (SLD) of primaquine has gametocidal activity, which does not cure the individual but does provide malaria transmission control.
Primaquine is a pro-drug that must be activated by the cytochrome P450 (CYP) enzyme system. Metabolism by the cytochrome P450 member 2D6 (CYP2D6) and cytochrome P450 nicotinamide adenine dinucleotide phosphate (NADPH):oxidoreductase (CPR) generates 2 hydroxylated active metabolites that generate hydrogen peroxide (H2O2). This causes significant oxidative stress to the malarial parasite and the host human cells. Individuals who are glucose-6-phosphate dehydrogenase (G6PD) deficient are particularly susceptible to oxidative stress and may experience acute hemolytic anemia (AHA). Before starting a course of primaquine, individuals should be tested for G6PD deficiency to ensure safe administration (1, 2). According to the FDA-approved drug label, individuals with severe G6PD deficiency should not take primaquine (Table 1) (1).
The World Health Organization (WHO) recommends that individuals with G6PD deficiency should be treated with a modified course of primaquine therapy. The recommended course for individuals with G6PD deficiency is a single dose once per week for 8 weeks, while the standard course is daily administration for 14 days (Table 2) (2). The Clinical Pharmacogenetics Implementation Consortium (CPIC) reports that the risk of adverse effects of primaquine therapy for G6PD-deficient individuals is dose-dependent, with the SLD regimen presenting the least risk (Table 3) (3).
Primaquine is contraindicated during pregnancy and is not recommended for breastfeeding individuals when the G6PD status of the baby is unknown (1, 2). Primaquine is not approved for individuals under 6 months of age. Individuals with acute illness that are prone to granulocytopenia or individuals taking another hemolytic medication are also contraindicated from taking primaquine. (1)
Chloroquine Therapy and <em>G6PD</em> Genotype
2023 May 16. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012–.
ABSTRACT
Chloroquine is used for the treatment of uncomplicated malaria and extra-intestinal amebiasis. Malaria is caused by infection of Plasmodium parasites. Chloroquine is active against the erythrocytic forms of susceptible strains of Plasmodium falciparum (P. falciparum), Plasmodium malariae (P. malariae), Plasmodium ovale (P. ovale), and Plasmodium Vivax (P. vivax). Chloroquine is not active against the gametocytes and the exoerythrocytic forms including the hypnozoite stage (P. vivax and P. ovale) of the Plasmodium parasites. Additionally, resistance to chloroquine and hydroxychloroquine has been reported in Plasmodium species, thus chloroquine therapy is not indicated if the infection arose in a region with known resistance. Chloroquine is used in first-line treatment of P. vivax malaria with primaquine. Studies have indicated chloroquine is effective against the trophozoites of Entamoeba histolytica (E. histolytica), which causes amebic dysentery, or amebiasis. (1) Chloroquine also has off-label uses for treatment of rheumatic diseases and has been investigated as a potential antiviral therapy as well as an adjuvant chemotherapy for several types of cancer. (2, 3, 4, 5)
Chloroquine accumulates in cellular acidic compartments such as the parasitic food vacuole and mammalian lysosomes, leading to alkalinization of these structures. This change in pH can impair the action of enzymes responsible for the formation of hemozoin by the parasite from ingestion of the host’s hemoglobin; this reaction occurs in the parasitic vacuole (6). Thus, chloroquine targets the blood-stage of the malaria parasites but cannot eliminate dormant hypnozoites and must be administered with a drug that targets the dormant parasitic form (1). Chloroquine, developed in the 1940s, has been superseded as the first-line recommended antimalarial therapy by both the US Centers for Disease Control (CDC) and World Health Organization (WHO), with the exceptions of during the first trimester of pregnancy or for malarial prophylaxis of a pregnant individual who is also deficient for glucose-6-phosphate dehydrogenase (G6PD) (7, 8). Among antimalarial medications, chloroquine is less likely than other medicines to cause hemolysis in G6PD-deficient individuals; however, the FDA-approved drug label states there is still a risk of hemolysis (Table 1) (1). In contrast, the Clinical Pharmacogenetics Implementation Consortium (CPIC) performed a systematic review of the available clinical literature and found low-to-no risk of acute hemolytic anemia for individuals with G6PD deficiency who take hydroxychloroquine or chloroquine (9) (Table 2). It should be noted that G6PD deficiency has a range of severity; CPIC advises caution for all medications when used by an individual with a severe G6PD deficiency with chronic non-spherocytic hemolytic anemia (CNSHA).
Guarana
2023 Jan 28. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012–.
ABSTRACT
Guarana is an extract of roasted and pulverized seeds of the plant Paullinia cupana which is indigenous to the Amazon Basin and whose major active components are caffeine and other xanthine alkaloids such as theophylline and theobromine. Guarana has been used as a stimulant and tonic to treat fatigue, decrease hunger and thirst and for headaches and dysmenorrhea. In conventional doses, guarana has few side effects and has not been linked to episodes of liver injury or jaundice.
Clopidogrel Therapy and <em>CYP2C19</em> Genotype
2012 Mar 8 [updated 2022 Dec 1]. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012–.
ABSTRACT
Clopidogrel (brand name Plavix) is an antiplatelet medicine that reduces the risk of myocardial infarction (MI) and stroke in individuals with acute coronary syndrome (ACS), and in individuals with atherosclerotic vascular disease (indicated by a recent MI or stroke, or established peripheral arterial disease) (1). Clopidogrel is also indicated in combination with aspirin for individuals undergoing percutaneous coronary interventions (PCI), including stent placement.
The effectiveness of clopidogrel depends on its conversion to an active metabolite, which is accomplished by the cytochrome P450 2C19 (CYP2C19) enzyme. Individuals who have 2 loss-of-function copies of the CYP2C19 gene are classified as CYP2C19 poor metabolizers (PM). Individuals with a CYP2C19 PM phenotype have significantly reduced enzyme activity and cannot activate clopidogrel via CYP2C19, which means the drug will have a reduced antiplatelet effect. Approximately 2% of Caucasians, 4% of African Americans, 14% of Chinese, and 57% of Oceanians are CYP2C19 PMs (2). The effectiveness of clopidogrel is also reduced in individuals who are CYP2C19 intermediate metabolizers (IM). These individuals have one loss-of-function copy of CYP2C19, with either one normal function copy or one increased function copy. The frequency of the IM phenotype is more than 45% in individuals of East Asian descent, more than 40% in individuals of Central or South Asian descent, 36% in the Oceanian population, approximately 30% in individuals of African descent, 20–26% in individuals of American, European, or Near Eastern descent, and just under 20% in individuals of Latino descent (2).
The 2022 FDA-approved drug label for clopidogrel includes a boxed warning on the diminished antiplatelet effect of clopidogrel in CYP2C19 PMs (Table 1). The warning states that tests are available to identify individuals who are CYP2C19 PMs, and to consider the use of another platelet P2Y12 (purinergic receptor P2Y, G-protein coupled 12) inhibitor in individuals identified as CYP2C19 PMs.
The 2022 Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for clopidogrel recommends that for individuals with ACS or non-ACS indications who are undergoing PCI, being treated for peripheral arterial disease (PAD), or stable coronary artery disease following MI, an alternative antiplatelet therapy (for example, prasugrel or ticagrelor) should be considered for CYP2C19 PMs if there is no contraindication (Table 2) (3). Similarly, CPIC strongly recommends that CYP2C19 IMs should avoid clopidogrel for ACS or PCI but makes no recommendations for other cardiovascular indications (Table 2). For neurovascular indications, CPIC recommends avoidance of clopidogrel for CYP2C19 PMs and consideration of alternative medications for both IMs and PMs if not contraindicated (Table 3) (3).
The Dutch Pharmacogenetics Working Group (DPWG) of the Royal Dutch Association for the Advancement of Pharmacy (KNMP) have also made antiplatelet therapy recommendations based on CYP2C19 genotype. For individuals with ACS who undergo PCI, they recommend an alternative antiplatelet agent in PMs, and for IMs they recommend choosing an alternative antiplatelet agent or doubling the dose of clopidogrel to 150 mg daily dose, 600 mg loading dose (Table 4) (4).
Oxycodone Therapy and <em>CYP2D6</em> Genotype
2022 Oct 4. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kane MS, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012–.
ABSTRACT
Oxycodone (brand names OxyContin, Roxicodone, Xtampza ER, and Oxaydo), is an opioid analgesic used for moderate to severe pain caused by various conditions for which alternative analgesic treatments are inadequate.(1) Oxycodone exerts its analgesic affects by binding to the mu-opioid receptors (MOR) in the central and peripheral nervous system. While it is an effective pain reliever, this agent also has a high potential for addiction, abuse, and misuse.
Oxycodone is metabolized by members of the cytochrome P450 (CYP) enzyme superfamily. The CYP3A4, CYP3A5, and CYP2D6 enzymes convert oxycodone to either less-active (CYP3A4 and CYP3A5) or more-active (CYP2D6) metabolites. Most of the analgesic effect is mediated by oxycodone itself, rather than its metabolites. Variation at the CYP3A4 and CYP3A5 loci leading to altered enzyme activity is rare. A handful of altered-function alleles are known, but there is no documented evidence to support altered oxycodone response in the presence of these variant alleles. The FDA approved drug label for oxycodone cautions that co-medication with CYP3A inhibitors or inducers may lead to altered pharmacokinetics and analgesia, but does not discuss genotype-based recommendations for prescribing (1).
Genetic variation at the CYP2D6 locus has conflicting evidence regarding altered response of individuals to oxycodone therapy. Thus, the Clinical Pharmacogenetics Implementation Consortium (CPIC) has determined that there is insufficient evidence to recommend alterations to standard clinical use based on CYP2D6 genotype (2). Similarly, the Dutch Pharmacogenetics Working Group (DPWG) of the Royal Dutch Association for the Advancement of Pharmacy (KNMP) recognizes the drug-gene interaction between CYP2D6 and oxycodone but states that the interaction does not affect analgesia achieved by the medication (3, 4). The PharmGKB online resource reports that drug labels in Switzerland (regulated by Swissmedic) state that CYP2D6 variation can alter oxycodone response (5, 6).
Interactions among drugs from polypharmacy may be further enhanced by genetic variation, but there are no professional recommendations to alter prescribing based on drug-drug-gene interactions. Regardless of genotype, oxycodone is contraindicated in individuals with significant respiratory depression, acute or severe bronchial asthma, known or suspect gastrointestinal obstruction, or known hypersensitivity to the medication (1).
Hepatitis C (HCV) Agents
2022 Feb 7. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012–.
ABSTRACT
The hepatitis C virus (HCV) is a small RNA virus belonging to the family flaviviridae and genus hepacivirus. The virion is approximately 50 nm in diameter and has an outer lipid associated envelop (E1 and E2) and inner nucleocapsid (Core). Within the nucleocapsid is a single molecule of single-stranded RNA of positive polarity approximately 9.5 kilobases in length. The RNA is transcribed into a large polyprotein that is subsequently cleaved into multiple polypeptides, labeled from the 5’ to 3’ end: core, envelope 1 and 2, and nonstructural proteins NS2, NS3, NS4 and NS5A and NS5B. The NS3 region encodes a viral helicase and protease. The NS5A region encodes a polypeptide that is essential for production and maintenance of the replicative complex. The NS5B region encodes a viral RNA dependent, RNA polymerase that is essential for replication. The NS3, NS5A and NS5B regions have been targeted with direct acting antiviral agents.
The initial agents used to treat chronic hepatitis C were interferon alfa, peginterferon and ribavirin. The antiviral activity of interferon and peginterferon is based upon their ability to stimulate interferon stimulated genes (ISGs) that have endogenous antiviral activities. Ribavirin is a nucleoside analogue that potentiates the effects of interferon against hepatitis C by as yet undefined mechanisms. Until 2010, the standard therapy of chronic hepatitis C was the combination of peginterferon and ribavirin given for 24 or 48 weeks. This combination led to sustained clearance of HCV and remission in disease in 40% to 50% of patients. Response rates were higher with certain HCV genotypes, so that response rates in patients with genotypes 2 and 3 were as high as 70% to 80%. Importantly, these remissions in disease have been shown to represent cure of the chronic viral infection, in that long term follow up demonstrated lack of HCV replication and resolution of disease activity in over 98% of patients. The shortcomings of peginterferon-ribavirin therapy were significant, most importantly the poor tolerance and side effects of this regimen. Thus, a high proportion of patients was intolerant or had contraindications to treatment. In 2010, three HCV-specific protease inhibitors were approved for use and introduced into practice: boceprevir, telaprevir and simeprevir. All three of these were specific to genotype 1 HCV and had little or no activity against genotypes 2 or 3 or the lesser common genotypes 4, 5 and 6. Triple therapy with peginterferon, ribavirin and a HCV-specific protease inhibitor (boceprevir, telaprevir or simeprevir) increased the response rate in patients with chronic hepatitis C, genotype 1 from 40%-45% to 65%-75%. A persistent difficulty, however, was the continued need to combine these agents with peginterferon and the considerable side effects which were worsened by these protease inhibitors.
An important advance in therapy of hepatitis C came in 2013 with the approval of an HCV specific RNA polymerase inhibitor, sofosbuvir. Sofosbuvir not only increased the response rate when combined with peginterferon and ribavirin, but also allowed for interferon-free treatment when combined with ribavirin, HCV protease inhibitors or a new class of agents that antagonized HCV NS5A activity. In 2014, all-oral HCV specific antiviral regimens were approved that yielded response rates in excess of 95% in patients with genotype 1. Furthermore, successful therapy required only 8 to 12 weeks of treatment in most patients and were extremely well tolerated. These all-oral regimens revolutionized therapy of hepatitis C, allowing treatment of virtually all patients regardless of severity of illness or co-morbid conditions with few side effects and durations of therapy of 8, 12 or 24 weeks. Other all oral regimens, including treatments for the less common genotypes of hepatitis C began to become available in 2015, 2016 and 2017. The several classes of agents that are combined in either a two-, three- or four-drug regimens include HCV RNA polymerase inhibitors (nucleoside and nonnucleoside), HCV NS5A antagonists and the HCV protease inhibitors. Several of these drug combinations have been formulated as single tablet or co-packaged regimens. These combination products made therapy easier to apply, but also resulted in the withdrawal of less successful agents, including boceprevir, telaprevir, daclatasvir, simeprevir and the four-drug combination of ombitasvir, dasabuvir, paritaprevir and ritonavir (Viekira Pak). Most currently used regimens are given for 8 to 12 weeks and yield response rates of 98% or more (Epclusa, Mavyret and Zepatier). Widespread application of these therapies to patients with chronic hepatitis C will likely decrease the morbidity and mortality of this disease and make significant inroads into decreasing the burden of chronic liver disease, cirrhosis, and hepatocellular carcinoma worldwide.
Diuretics
2021 Oct 13. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012–.
ABSTRACT
Diuretics constitute a large family of medications that increase urine flow and induce urinary sodium loss and are widely used for therapy of hypertension, congestive heart failure, and edematous states. Diuretics in current use (and the year of their approval for use in the United States) include chlorothiazide (1958), hydrochlorothiazide (1959), bendroflumethiazide (1959), spironolactone (1960), chlorthalidone (1960), methyclothiazide (1961), polythiazide (1961), triamterene (1964), furosemide (1966), ethacrynic acid (1967), metolazone (1973), bumetanide (1983), indapamide (1983), amiloride (1986), acetazolamide (1986), torsemide (1993), and eplerenone (2002). Diuretics are typically classified as thiazide diuretics (bendroflumethiazide, chlorothiazide, chlorthalidone, hydrochlorothiazide, indapamide, metolazone and polythiazide), loop diuretics (bumetanide, ethacrynic acid, furosemide, and torsemide), and potassium-sparing agents (amiloride, eplerenone, spironolactone, and triamterene). The carbonic anhydrase blockers acetazolamide (1986) and methazolamide (1959) are also diuretics, but are more commonly used for the therapy of glaucoma.
Diuretics are some of the most frequently used medications in medicine and are usually well tolerated. Common side effects are those that are caused by the diuresis and mineral loss such as weakness, dizziness, electrolyte imbalance, low sodium and potassium. Diuretics have not been associated with an appreciable increased rate of serum aminotransferase elevations and have rarely been associated with clinically apparent liver injury. Isolated case reports of idiosyncratic hepatotoxicity due to diuretics have been published, but there have been virtually no case series on individual diuretics or even whole class of drugs. The case reports that have been published provide only a very general pattern of injury that has not provided a clear clinical signature or suggestion that hepatotoxicity is a class effect among the thiazides and the loop diuretics. Switching from one diuretic to another has not been reported in any systematic fashion. Most information on hepatotoxicity is available on the commonly used diuretics which include (and the number of prescriptions filled in 2007 for each): hydrochlorothiazide (45 million), furosemide (37 million), triamterene (21 million), spironolactone (8 million), and metolazone, bumetanide, indapamide and torsemide (1 to 2 million each). Diuretics implicated in rare cases of drug induced liver injury include hydrochlorothiazide, acetazolamide, amiloride, spironolactone and triamterene.
The thiazide and loop diuretics are discussed as a class; the other diuretics as individual agents. Selected references are given together at the end of this introductory section.
Covid-19 Vaccines
2021 May 3. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012–.
ABSTRACT
The Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2) is the cause of the pandemic of coronavirus disease (COVID-19) that was first detected in December 2019 in Wuhan, China and subsequently spread globally. By March 2020, COVID-19 was declared a global pandemic and within a year it accounted for more than 100 million cases and 2 million deaths. Also, within a year of its detection, vaccines against SARS-CoV-2 were developed using several methodologies including mRNA-, adenoviral vector- and recombinant DNA-technology. Several of these vaccines have been evaluated in large, placebo-controlled trials and found to be both safe and effective. Adverse events have been mild-to-moderate local reactions and transient systemic symptoms such as fatigue, nausea and headache. No hepatic specific adverse events have been described, although rare reports of thrombotic thrombocytopenia have occurred with the adenoviral based vaccines that sometimes involve portal or hepatic vein thromboses and some degree of liver dysfunction.
Vanzacaftor, Tezacaftor and Deutivacaftor
2025 Jan 15. Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006–.
ABSTRACT
No information is available on milk or infant serum levels of vanzacaftor or deutivacaftor. Information from mother-infant pairs with elexacaftor, ivacaftor and tezacaftor indicates that tezacaftor has low levels in milk and infant serum. Deutivacaftor is a deuterated form of ivacaftor that has slower clearance, a longer half-life and greater maternal exposure. Transient mild elevations in bilirubin and liver enzymes during maternal therapy have been reported in breastfed infants whose mothers were taking another combination product containing tezacaftor and ivacaftor. Enzyme levels tended to normalize during continued breastfeeding. Until more data are available, monitoring of infant bilirubin and liver enzymes might be advisable during breastfeeding with maternal vanzacaftor, tezacaftor and deutivacaftor therapy.[1] Congenital cataracts in breastfed infants has been reported in the infants of mothers who took drugs of this class during pregnancy. Examination of breastfed infants for cataracts has been recommended.[2] Anecdotal evidence indicates that these types of drugs in breastmilk may moderate cystic fibrosis in breastfed infants.
Codeine
2021 Aug 16. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006–.
ABSTRACT
Maternal use of codeine during breastfeeding can cause infant drowsiness, central nervous system depression and possibly even death, with pharmacogenetics possibly playing a role.[1,2] Newborn infants seem to be particularly sensitive to the effects of even small dosages of narcotic analgesics. Once the mother's milk comes in, it is best to provide pain control with a nonnarcotic analgesic and limit maternal intake of oral codeine to 2 to 4 days at a low dosage with close infant monitoring, especially in the outpatient setting.[2-4] If the baby shows signs of increased sleepiness (more than usual), difficulty breastfeeding, breathing difficulties, or limpness, a physician should be contacted immediately.[5] Excessive sedation in the mother often correlates with excess sedation in the breastfed infant. Following these precautions can lower the risk of neonatal sedation.[6] Numerous professional organizations and regulatory agencies recommend that other agents are preferred over codeine or to avoid codeine completely during breastfeeding;[7-11] however, other opioid alternatives have been studied less and may not be safer.[12,13]
Dihydrocodeine
2021 Jun 21. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006–.
ABSTRACT
Maternal use of oral narcotics during breastfeeding can cause infant drowsiness, central nervous system (CNS) depression and even death. Like codeine, pharmacogenetics probably plays a role in the extent of CNS depression. Newborn infants seem to be particularly sensitive to the effects of even small dosages of narcotic analgesics. Dihydrocodeine possibly caused severe respiratory depression in one newborn infant whose mother was taking the drug for cough. Once the mother's milk comes in, it is best to provide pain control with a nonnarcotic analgesic and limit maternal intake of hydromorphone to a few days at a low dosage with close infant monitoring. If the baby shows signs of increased sleepiness (more than usual), difficulty breastfeeding, breathing difficulties, or limpness, a physician should be contacted immediately. Because there is little published experience with dihydrocodeine during breastfeeding, an alternate drug may be preferred, especially while nursing a newborn or preterm infant.
Ivacaftor
2021 Apr 19. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006–.
ABSTRACT
Information from one maternal-infant pair with ivacaftor and lumacaftor indicates that maternal ivacaftor therapy produce low levels in milk. An international survey of cystic fibrosis centers found no adverse effects in breastfed infants of mothers taking these drugs. A task force respiratory experts from Europe, Australia and New Zealand found that these drugs are probably safe during breastfeeding.[1] One breastfed infant had transient elevations in bilirubin and liver enzymes during maternal therapy that could not definitively be attributed to the drugs in breastmilk. Until more data are available, monitoring of infant bilirubin and liver enzymes might be advisable during breastfeeding with maternal ivacaftor therapy. Examination of breastfed infants for cataracts has also been recommended.[2]
Tezacaftor and Ivacaftor
2021 Apr 19. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006–.
ABSTRACT
Information from one maternal-infant pair with ivacaftor and lumacaftor indicates that maternal ivacaftor therapy produce low levels in milk. An international survey of cystic fibrosis centers found no adverse effects in breastfed infants of mothers taking these drugs. A task force respiratory experts from Europe, Australia and New Zealand found that these drugs are probably safe during breastfeeding.[1] One breastfed infant had transient elevations in bilirubin and liver enzymes during maternal therapy that could not definitively be attributed to the drugs in breastmilk. Until more data are available, monitoring of infant bilirubin and liver enzymes might be advisable during breastfeeding with maternal tezacaftor and ivacaftor therapy. Examination of breastfed infants for cataracts has also been recommended.[2]
Lumacaftor and Ivacaftor
2021 Apr 19. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006–.
ABSTRACT
Information from one maternal-infant pair with ivacaftor and lumacaftor indicates that maternal ivacaftor therapy produce low levels in milk. An international survey of cystic fibrosis centers found no adverse effects in breastfed infants of mothers taking these drugs. A task force respiratory experts from Europe, Australia and New Zealand found that these drugs are probably safe during breastfeeding.[1] One breastfed infant had transient elevations in bilirubin and liver enzymes during maternal therapy that could not definitively be attributed to the drugs in breastmilk. Until more data are available, monitoring of infant bilirubin and liver enzymes might be advisable during breastfeeding with maternal lumacaftor and ivacaftor therapy. Examination of breastfed infants for cataracts has also been recommended.[2]
Diagnostic Tests for Diabetes Mellitus
2025 Feb 7. In: Feingold KR, Anawalt B, Blackman MR, Boyce A, Chrousos G, Corpas E, de Herder WW, Dhatariya K, Dungan K, Hofland J, Kalra S, Kaltsas G, Kapoor N, Koch C, Kopp P, Korbonits M, Kovacs CS, Kuohung W, Laferrère B, Levy M, McGee EA, McLachlan R, New M, Purnell J, Sahay R, Shah AS, Singer F, Sperling MA, Stratakis CA, Trence DL, Wilson DP, editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000–.
ABSTRACT
In this chapter, indications for screening for diabetes mellitus are reviewed. Criteria for diagnosis are fasting plasma glucose ≥ 126 mg/dl (7.0 mmol/l) or random glucose ≥200 mg/dl (11.1 mmol/l) with hyperglycemic symptoms, hemoglobin A1c (HbA1c) ≥6.5%, and oral glucose tolerance testing (OGTT) 2-h glucose ≥200 mg/dl (11.1 mmol/l) after 75 g of glucose. One-step and two-step strategies for diagnosing gestational diabetes using pregnancy-specific criteria as well as use of the 2-h 75-g OGTT for the postpartum testing of women with gestational diabetes (4-12 weeks after delivery) are described. Testing for other forms of diabetes with unique features are reviewed, including the recommendation to use the 2-h 75 g OGTT to screen for cystic fibrosis-related diabetes and post-transplantation diabetes, fasting glucose test for HIV positive individuals, and genetic testing for monogenic diabetes syndromes including neonatal diabetes and maturity-onset diabetes of the young (MODY). Elevated measurements of pancreatic islet autoantibodies (e.g., to the 65-KDa isoform of glutamic acid decarboxylase (GAD65), tyrosine phosphatase related islet antigen 2 (IA-2), insulin (IAA), and zinc transporter (ZnT8)) suggest autoimmune type 1 diabetes (vs type 2 diabetes). IAA is primarily measured in youth. The use of autoantibody testing in diabetes screening programs is recommended in first degree relatives of an individual with type 1 diabetes or in research protocols. C-peptide measurements can be helpful in identifying those who have type 1 diabetes (low or undetectable c-peptide) from those who may have type 2 or monogenic diabetes. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.
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