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1.
Acta Biomed ; 94(3): e2023098, 2023 06 14.
Article in English | MEDLINE | ID: mdl-37326274

ABSTRACT

BACKGROUND AND AIM: Vitamin A toxicity is uncommon, but when it occurs can be serious and even fatal. A case vitamin A intoxication with high levels in liver tests, thrombocytopenia and appearance virosis. Laboratory testing is one of the most widely used diagnostic interventions supporting medical decisions of this phenomenon are necessary. CASE REPORT: Here, we report a case vitamin A intoxication with high levels in liver tests, thrombocytopenia and appearance virosis. The patient showed several clinical signs abdominal pain, including mild anemia and thrombocytopenia. CONCLUSIONS: We believe that Laboratory testing is one of the most widely used diagnostic interventions supporting medical decisions, and further investigations regarding the etiology and prevalence of this phenomenon are necessary. (www.actabiomedica.it).


Subject(s)
Anemia , Hypervitaminosis A , Thrombocytopenia , Humans , Hypervitaminosis A/complications , Hypervitaminosis A/diagnosis , Vitamin A , Anemia/etiology , Thrombocytopenia/chemically induced , Thrombocytopenia/diagnosis
2.
J Ren Nutr ; 32(3): 275-281, 2022 05.
Article in English | MEDLINE | ID: mdl-34103212

ABSTRACT

OBJECTIVE: Hypervitaminosis A is well-described but overlooked in chronic kidney disease (CKD) and has been associated with hypercalcemia, contributing to mineral bone disease. Our objective is to assess prevalence of hypervitaminosis A and its association with bone health in an advanced-CKD population. METHODS: We performed a retrospective review of 58 children with CKD 4-5 to examine the association between vitamin A levels and bone health and compared these values between a primarily formula-fed (FF) and nonprimarily formula-fed cohort (NFF). RESULTS: Fifty-six of 58 patients (97%) had hypervitaminosis A with a mean vitamin A level of 1,475 ± 597 mcg/dL. When compared with the upper limit of normal vitamin A level for age, the FF group's vitamin A level was 2.9x upper limit of normal and the NFF group's vitamin A level was 2.2x upper limit of normal (P = .02). The mean calcium level was 10.3 mg/dL in the FF group and 9.8 mg/dL in the NFF group (P = .057). Percent of patients lower than, within, or greater than goal parathyroid hormone range was statistically significant with 15 (62%) of the FF group lower than goal and 16 (72%) of the NFF cohort greater than goal (P = .006). CONCLUSIONS: We concluded vitamin A and calcium levels are higher in the FF versus the NFF population. FF patients are more likely to have parathyroid hormone levels lower than the goal range, placing them at risk for adynamic bone disease. We recommend monitoring vitamin A levels as part of routine nutritional assessments and dietary interventions to prevent hypervitaminosis A to improve bone health in late CKD.


Subject(s)
Bone Diseases , Hypervitaminosis A , Renal Insufficiency, Chronic , Bone Diseases/complications , Calcium , Child , Female , Humans , Hypervitaminosis A/complications , Male , Parathyroid Hormone , Renal Insufficiency, Chronic/complications , Vitamin A , Vitamin D
3.
Article in English | MEDLINE | ID: mdl-31546693

ABSTRACT

Rubella is a systemic virus infection that is usually mild. It can, however, cause severe birth defects known as the congenital rubella syndrome (CRS) when infection occurs early in pregnancy. As many as 8%-13% of children with CRS developed autism during the rubella epidemic of the 1960s compared to the background rate of about 1 new case per 5000 children. Rubella infection and CRS are now rare in the U.S. and in Europe due to widespread vaccination. However, autism rates have risen dramatically in recent decades to about 3% of children today, with many cases appearing after a period of normal development ('regressive autism'). Evidence is reviewed here suggesting that the signs and symptoms of rubella may be due to alterations in the hepatic metabolism of vitamin A (retinoids), precipitated by the acute phase of the infection. The infection causes mild liver dysfunction and the spillage of stored vitamin A compounds into the circulation, resulting in an endogenous form of hypervitaminosis A. Given that vitamin A is a known teratogen, it is suggested that rubella infection occurring in the early weeks of pregnancy causes CRS through maternal liver dysfunction and exposure of the developing fetus to excessive vitamin A. On this view, the multiple manifestations of CRS and associated autism represent endogenous forms of hypervitaminosis A. It is further proposed that regressive autism results primarily from post-natal influences of a liver-damaging nature and exposure to excess vitamin A, inducing CRS-like features as a function of vitamin A toxicity, but without the associated dysmorphogenesis. A number of environmental factors are discussed that may plausibly be candidates for this role, and suggestions are offered for testing the model. The model also suggests a number of measures that may be effective both in reducing the risk of fetal CRS in women who acquire rubella in their first trimester and in reversing or minimizing regressive autism among children in whom the diagnosis is suspected or confirmed.


Subject(s)
Autistic Disorder/chemically induced , Hypervitaminosis A/complications , Liver Diseases/complications , Rubella Syndrome, Congenital/chemically induced , Rubella/physiopathology , Vitamin A/toxicity , Humans , Hypervitaminosis A/chemically induced , Liver/metabolism , Rubella virus/physiology , Vitamin A/metabolism
4.
Ir Med J ; 112(6): 953, 2019 06 17.
Article in English | MEDLINE | ID: mdl-31538442

ABSTRACT

There is an increasing literature with regard to vitamin D supplementation in Multiple Sclerosis (MS). We report the case of a 45 year-old male with MS who presented with symptomatic hypercalcaemia secondary to self-supplementation of vitamin D3 purchased online. Treatment was with IV hydration, glucocorticoids, calcitonin and bisphosphonates. This case highlights a lack of consensus guidance regarding safe vitamin D supplementation dosages and the importance of a thorough history with regard to non-prescribed supplements, particularly those easily available online.


Subject(s)
Hypercalcemia/etiology , Hypervitaminosis A/complications , Multiple Sclerosis/complications , Dietary Supplements , Humans , Male , Middle Aged
5.
BMC Musculoskelet Disord ; 20(1): 287, 2019 Jun 15.
Article in English | MEDLINE | ID: mdl-31202274

ABSTRACT

BACKGROUND: A vitamin A derivative, 13-cis-retinoic acid (isotretinoin), has been administered to treat several types of pediatric cancer and has improved survival rates in patients despite being known to induce premature epiphyseal closure. As the number of patients treated by 13-cis-retinoic acid increases, demands for salvage treatment after systemic retinoid therapy are emerging. However, few studies have described the surgical treatment of this disease. CASE PRESENTATION: We report a case with bilateral varus knee deformity due to premature epiphyseal closure that occurred during treatment with isotretinoin for neuroblastoma. The patient was successfully treated with correction osteotomy using a Taylor spatial frame in the right knee joint and femoral closed wedge osteotomy using a locking plate in left knee joint. Histopathological examination of the growth plate showed polar irregularity of chondrocytes and decreased cartilage matrix without apoptosis. In contrast, arthroscopic findings showed an intact joint surface. No recurrence of varus deformity was evident on follow-up at 1 year. CONCLUSIONS: To the best of our knowledge, this represents the first report of correction osteotomy for varus knee deformity due to premature epiphyseal closure that occurred during treatment with isotretinoin.


Subject(s)
Growth Plate/physiopathology , Hypervitaminosis A/complications , Knee Joint/surgery , Osteoarthritis, Knee/surgery , Osteotomy/methods , Bone Plates , Child , Female , Femur/diagnostic imaging , Femur/physiopathology , Femur/surgery , Humans , Hypervitaminosis A/chemically induced , Hypervitaminosis A/physiopathology , Isotretinoin/adverse effects , Magnetic Resonance Imaging , Neuroblastoma/drug therapy , Osteoarthritis, Knee/diagnostic imaging , Osteoarthritis, Knee/etiology , Osteotomy/instrumentation , Tibia/diagnostic imaging , Tibia/physiopathology , Tibia/surgery , Treatment Outcome
6.
Transplant Proc ; 51(1): 90-91, 2019.
Article in English | MEDLINE | ID: mdl-30655144

ABSTRACT

Herein we report a case of liver dysfunction caused by consumption of vitamin A supplements leading to liver transplantation. The patient was a 48-year-old male with a medical history of congenital ichthyosiform erythroderma in treatment with vitamin A until 12 years of age, at which point he discontinued the supplements because he had developed ascites. Liver cirrhosis was diagnosed as secondary to hypervitaminosis A on the basis of histologic examination of liver biopsy and the absence of other potential causes of chronic liver disease. Despite interruption of administration of vitamin A, the patient continued to deteriorate over the years, with development of portal hypertension signs. His medical conditions were aggravated with the development of hepatic insufficiency manifested by refractory ascites, renal insufficiency, and severe encephalopathy and he underwent orthotopic liver transplantation, followed by disappearance of all signs of portal hypertension. This case highlights the need to take a careful history of consumption of vitamin A when evaluating a patient with liver failure.


Subject(s)
Dietary Supplements/poisoning , Hypervitaminosis A/complications , Liver Cirrhosis/chemically induced , Liver Cirrhosis/surgery , Liver Transplantation , Humans , Hypertension, Portal/chemically induced , Ichthyosiform Erythroderma, Congenital/complications , Liver/pathology , Male , Middle Aged
7.
Injury ; 48(7): 1475-1479, 2017 Jul.
Article in English | MEDLINE | ID: mdl-28511966

ABSTRACT

BACKGROUND: The aim was to research the molecular changes of bone cells induced by excessive dose of vitamin A, and analyze molecular mechanism underlying spontaneous fracture. METHODS: The gene expression profile of GSE29859, including 4 cortical bone marrow samples with excessive doses of Vitamin A and 4 control cortical bone marrow samples, was obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DGEs) between cortical bone marrow samples and control samples were screened out and pathway enrichment analysis was undertaken. Based on the MSigDB database, the potential regulatory transcription factors (TFs) were identified. RESULTS: A total of 373 DEGs including 342 up- and 31 down-regulated genes were identified. These DEGs were significantly enriched in pathways of protein processing in endoplasmic reticulum, ubiquitin mediated proteolysis and glycerophospholipid metabolism. Finally, the most significant regulatory TFs were obtained, including E2F Transcription Factor 1 (E2F1), GA Binding Protein Transcription Factor (GABP), Nuclear Factor, Erythroid 2-Like 2 (NRF2) and ELK1, Member of ETS Oncogene Family (ELK1). CONCLUSION: Key TFs including E2F1, GABP, NRF2 and ELK1 and their targets genes such as Ube2d3, Uba1, Phb2 and Tomm22 may play potential key roles in spontaneous fracture induced by hypervitaminosis A. The pathways of protein processing in endoplasmic reticulum, ubiquitin mediated proteolysis and glycerophospholipid metabolism may be key mechanisms involved in spontaneous fracture induced by hypervitaminosis A. Our findings will provide new insights for the target selection in clinical application to prevent spontaneous fracture induced by hypervitaminosis A.


Subject(s)
Bone Marrow Cells , Cortical Bone , Fractures, Spontaneous , Gene Expression Regulation , Hypervitaminosis A , Transcription Factors , Animals , Male , Rats , Bone Marrow Cells/drug effects , Bone Marrow Cells/metabolism , Cortical Bone/drug effects , Cortical Bone/metabolism , E2F1 Transcription Factor/metabolism , Endoplasmic Reticulum/metabolism , Endoplasmic Reticulum Stress , ets-Domain Protein Elk-1/metabolism , Fractures, Spontaneous/etiology , Fractures, Spontaneous/genetics , Gene Expression Regulation/drug effects , Gene Expression Regulation/genetics , Hypervitaminosis A/complications , Hypervitaminosis A/physiopathology , NF-E2-Related Factor 2/metabolism , Protein Transport , Signal Transduction , Transcription Factors/metabolism , Transcriptome/drug effects , Vitamin A/pharmacology
8.
Nefrología (Madr.) ; 37(1): 61-67, ene.-feb. 2017. ilus, tab
Article in English | IBECS | ID: ibc-160600

ABSTRACT

Background: Despite well-documented risks, injectable supplements containing high doses of vitamins are commonly used. Objectives: To describe acute kidney injury (AKI) as a complication of vitamin intoxication. Methods: Our series consisted of 16 patients with kidney complications resulting from the use of veterinary intramuscular injection supplements of vitamin A, D and E. The patients were admitted to two referral hospitals in Fortaleza (Brazil) between January 2010 and January 2015. Results: Patients’ mean age was 28.3±8.9 years (19-53 years), and 11 (68.7%) were male. Main signs and symptoms upon admission were nausea (68.7%), vomiting (62.5%), weight loss (43.7%), epigastric pain (31.2%) and headache (31.2%). At hospital admission the mean laboratory values were: hemoglobin 10±2.0g/dL (6.1-14.2), leukocytes 10,542 ± 4871/mm3 (4100-5,100), creatinine 3.9 ± 5.2mg/dL (0.7-22) and urea 91 ± 88mg/dL (22-306), respectively. Serum calcium was 12 ± 2.2 mg/dL (8.8-15.5), 24-h urine calcium was 575 ± 329 mg (10.7-1058), serum PTH was 55 ± 141pg/mL (2-406), and serum vitamin D concentration was 135 ± 75ng/mL (22-265). Using KDIGO criteria, AKI was diagnosed in 13 patients (81.2%), classified as stage 1 (n = 3), stage 2 (n = 3) or stage 3 (n = 7). No deaths occurred in the study period. Conclusions: Excessive use of veterinary vitamin supplements containing high doses of vitamin A, D and E was associated with AKI. Hypercalcaemia, which was a common finding, appears to be a contributing factor to the development of this type of AKI (AU)


Antecedentes: Suplementos inyectables que contienen altas dosis de vitaminas son utilizados con frecuencia, a pesar de los riesgos bien documentados. Objetivo: Describir la ocurrencia de daño renal agudo (IRA) como complicación de intoxicación por suplementos vitamínicos. Métodos: Esta es una serie de 16 pacientes con complicaciones renales resultantes de la utilización de inyección intramuscular de suplementos veterinarios con vitaminas A, D y E. Los pacientes fueron ingresados en 2 hospitales de referencia en Fortaleza (Brasil), entre enero de 2010 y enero de 2015. Resultados: La edad media de los pacientes fue de 28,3 ± 8,9 años (19-53 años) y 11 (68,7%) eran varones. Signos y síntomas principales al ingreso fueron náuseas (68,7%), vómitos (62,5%), pérdida de peso (43,7%), dolor epigástrico (31,2%) y cefalea (31,2%). Al ingreso en el hospital los valores medios de laboratorio fueron: hemoglobina 10 ± 2,0g/dL (6,1+14,2), leucocitos 10.542 ± 4.871/mm3 (4.100-15.100), creatinina 3,9 ± 5,2mg/dL (0,7-22) y urea 91 ± 88mg/dL (22-306), respectivamente. El nivel de calcio sérico fue de 12 ± 2,2 mg/dL (8,8-15,5), el de calcio en orina de 24 h fue de 575 ± 329 mg (10,7-1.058), el de PTH sérico fue de 55 ± 141 pg/mL (2-406) y el nivel de vitamina D sérica fue de 135 ± 75 ng/mL (22-265). Utilizando criterios KDIGO, se diagnosticó IRA en 13 pacientes (81,2%); fueron clasificadas como clase 1 (n = 3), clase 2 (n = 3) y clase 3 (n = 7). No hubo muertes en el período de estudio. Conclusiones: El uso excesivo de suplementos vitamínicos veterinarios que contienen altas dosis de vitamina A, D y E se asoció con IRA. La hipercalcemia, un hallazgo común, parece ser un factor que contribuye al desarrollo de este tipo de IRA (AU)


Subject(s)
Humans , Male , Female , Young Adult , Adult , Middle Aged , Acute Kidney Injury/chemically induced , Vitamin D/poisoning , Vitamin E/poisoning , Hypervitaminosis A/complications , Veterinary Drugs/adverse effects , Dietary Supplements/adverse effects , Injections, Intramuscular
9.
Arch Dis Child ; 102(6): 556-558, 2017 06.
Article in English | MEDLINE | ID: mdl-27272974

ABSTRACT

A 4-year-old boy presented with severe bone pains, refusal to walk, diffuse bony swelling of forelimbs, skin changes and abdominal pain, with symptoms evolving over 6 weeks. Blood screening tests were normal except for raised aspartate aminotransferase (AST). Radiographs revealed thickened periosteum, widening of the diaphyses of long bones and lifted periosteum in mid-shaft of ulnae and right femur. Skeletal scintigraphy showed a high uptake of radionuclide at clinically affected and unaffected sites, suggestive of multifocal osteoblastic skeletal lesions. After repeated enquiries, his parents admitted to giving him massive doses of preformed vitamin A for over 3 months as 'health tablets'. Surprisingly, he did not have overt liver disease typically found with much smaller doses, although the dermal changes and musculoskeletal pathology were florid. He made a full clinical recovery within 2 months of cessation of vitamin A.


Subject(s)
Bone Diseases/chemically induced , Hypervitaminosis A/complications , Pain/chemically induced , Bone Diseases/diagnostic imaging , Child, Preschool , Drug Administration Schedule , Humans , Hypervitaminosis A/diagnostic imaging , Male , Pain/diagnostic imaging , Radiography , Radionuclide Imaging , Vitamin A/administration & dosage
12.
Surv Ophthalmol ; 61(4): 506-11, 2016.
Article in English | MEDLINE | ID: mdl-26656927

ABSTRACT

An infant presented with bilateral disk edema and an acute left sixth cranial nerve (CN VI) palsy because of pseudotumor cerebri (PTC). PTC is rare in infants where it is often associated with endocrine abnormalities, medications, viral infections, systemic conditions, and nutritional etiologies such as vitamin A toxicity. We report a case of PTC in an infant associated with hypervitaminosis A with an unlikely source-a common prenatal vitamin.


Subject(s)
Hypervitaminosis A/complications , Optic Nerve/diagnostic imaging , Pseudotumor Cerebri/diagnosis , Vitamin A/adverse effects , Diagnosis, Differential , Female , Humans , Infant , Magnetic Resonance Imaging , Pseudotumor Cerebri/etiology , Vitamins/adverse effects
13.
Pediatr Nephrol ; 30(2): 317-25, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25119682

ABSTRACT

BACKGROUND: Vitamin A accumulates in renal failure, but the prevalence of hypervitaminosis A in children with predialysis chronic kidney disease (CKD) is not known. Hypervitaminosis A has been associated with hypercalcemia. In this study we compared dietary vitamin A intake with serum retinoid levels and their associations with hypercalcemia. METHODS: We studied the relationship between vitamin A intake, serum retinoid levels, and serum calcium in 105 children with CKD stages 2-5 on dialysis and posttransplant. Serum retinoid measures included retinol (ROH), its active retinoic acid (RA) metabolites [all-trans RA (at-RA) and 13-cis RA] and carrier proteins [retinol-binding protein-4 (RBP4) and transthyretin (TTR)]. Dietary vitamin A intake was assessed using a food diary. RESULTS: Twenty-five children were in CKD 2-3, 35 in CKD 4-5, 23 on dialysis and 22 posttransplant; 53 % had vitamin A intake above the Reference Nutrient Intake (RNI) value. Children receiving supplemental feeds compared with diet alone had higher vitamin A intake (p = 0.02) and higher serum ROH (p < 0.001). Notably, increased ROH was seen as early as CKD stage 2. For every 10 ml/min/1.73 m(2) fall in estimated glomerular filtration rate (eGFR), there was a 13 % increase in ROH. RBP4 levels were increased in CKD 3-5 and dialysis patients. The lowest ratios of ROH:RBP4 were seen in dialysis compared with CKD 2-3 (p = 0.03), suggesting a relative increase in circulating RBP4. Serum ROH, RBP4 and at-RA were associated with serum calcium. On multivariable analysis RBP4 levels and alfacalcidol dose were significant predictors of serum calcium (model R (2) 32 %) in dialysis patients. CONCLUSIONS: Hypervitaminosis A is seen in early CKD, with highest levels in children on supplemental feeds compared with diet alone. Serum retinoid levels significantly predict hypercalcemia.


Subject(s)
Hypercalcemia/etiology , Hypervitaminosis A/complications , Renal Insufficiency, Chronic/blood , Renal Insufficiency, Chronic/complications , Adolescent , Child , Child, Preschool , Chromatography, High Pressure Liquid , Diet , Female , Humans , Infant , Male
16.
Ann Am Thorac Soc ; 11(8): 1244-7, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25188737

ABSTRACT

Hypercalcemia is a rare complication of hypervitaminosis A. We report a pediatric patient with cystic fibrosis (CF) and pancreatic insufficiency who was found to have hypervitaminosis A causing hypercalcemia, complicated by nephrocalcinosis and renal impairment. The patient is a 4-year-old girl with pancreatic-insufficient CF, gastroesophageal reflux, oral aversion, and failure to thrive requiring gastrostomy tube placement. She was prescribed Source CF vitamins, but rarely received the full dose, due to emesis and intolerance. She had routine annual labs that revealed hypercalcemia with elevated blood urea nitrogen and creatinine, which were not present in her previous annual labs. Upon further questioning, her mother reported that she seemed more fatigued for a few weeks, had abdominal pain, and was urinating more frequently. Upon admission to the hospital, laboratory results revealed elevated HCO3, while serum levels of potassium, phosphorus, and albumin were within normal limits. Vitamin D (25-hydroxy) level was low, and vitamin A level was elevated. Extensive metabolic and hormonal workup for the etiology of the hypercalcemia revealed evidence of chronic renal insufficiency and elevated vitamin A levels. She had a renal ultrasound that revealed bilateral nephrocalciosis. Diagnosis of chronic hypervitaminosis A complicated by hypercalcemia was made and was managed by holding vitamin A supplements, aggressive diuresis, and prednisolone. This case emphasizes the importance of regular vitamin A monitoring in patients with CF. There is a wide variability for the lowest intake required to cause toxicity, and the lower limit to cause toxicity has not been determined.


Subject(s)
Calcium/blood , Cystic Fibrosis/complications , Hypercalcemia/etiology , Hypervitaminosis A/complications , Vitamin A/blood , Child, Preschool , Cystic Fibrosis/blood , Female , Humans , Hypercalcemia/blood , Hypervitaminosis A/blood
18.
West Indian med. j ; 63(1): 105-108, Jan. 2014.
Article in English | LILACS | ID: biblio-1045799

ABSTRACT

Vitamin A toxicity is a well-described medical condition with a multitude of potential presenting signs and symptoms. It can be divided into acute and chronic toxicity. Serum vitamin A concentrations are raised in chronic renal failure even with ingestion of less than the usual toxic doses. Hypercalcaemia can occasionally be associated with high levels of vitamin A but it is rare. In this report, we describe a 67-year old female patient with chronic kidney disease who was taking vitamin A supplements for approximately 10 years. The patient had worsening of her chronic kidney disease over the last years and developed chronic hypercalcaemia. Her vitamin A level was elevated with a daily intake of 7000 IU. The vitamin A supplement was stopped. A few months later, vitamin A level diminished substantially and serum calcium levels returned to normal.


La toxicidad de la vitamina A es una condición médica bien descrita que presenta un sinnúmero de potenciales signos y síntomas. Puede ser dividida en toxicidad aguda y crónica. Las concentraciones séricas de vitamina A se elevan con la insuficiencia renal crónica, incluso con la ingestión de dosis tóxicas por debajo de lo habitual. En ocasiones, la hipercalcemia puede estar asociada con altos niveles de vitamina A, pero esto raramente ocurre. En este informe, describimos a una paciente de 67 años de edad con enfermedad renal crónica, que estuvo tomando suplementos de vitamina A por aproximadamente 10 años. La paciente sufrió un empeoramiento de su enfermedad renal crónica en los últimos años, y desarrolló hipercalcemia crónica. Su nivel de vitamina A se elevó con una ingesta diaria de 7000 UI. El suplemento de vitamina A fue suspendido. Unos meses más tarde, el nivel de vitamina A nivel disminuyó sustancialmente, y los niveles de calcio sérico volvieron a la normalidad.


Subject(s)
Humans , Female , Aged , Hypervitaminosis A/complications , Renal Insufficiency, Chronic/blood , Hypercalcemia/etiology
19.
Med Sci Monit ; 19: 579-83, 2013 Jul 15.
Article in English | MEDLINE | ID: mdl-23852388

ABSTRACT

Mefloquine use has been linked to severe gastrointestinal and neuropsychiatric adverse effects, including cognitive disturbances, anxiety, depression, psychosis, and violence. The adverse effects of the drug are thought to result from the secondary consequences of hepatocellular injury; in fact, mefloquine is known to cause a transient, anicteric chemical hepatitis. However, the mechanism of mefloquine-associated liver damage and the associated neuropsychiatric and behavioral effects of the drug are not well understood. Mefloquine and other 8-amino-quinolines are the only antimalarial drugs that target the liver-stage malaria parasites, which selectively absorb vitamin A from the host. Vitamin A is also stored mainly in the liver, in potentially poisonous concentrations. These observations suggest that both the therapeutic effectiveness of mefloquine and its adverse effects are related to the ability of the 8-aminoquinolines to alter the metabolism of retinoids (vitamin A and its congeners). Several lines of evidence support the hypothesis that mefloquine neurotoxicity and other adverse effects reflect an endogenous form of hypervitaminosis A due to a process involving: mefloquine-induced dehydrogenase inhibition; the accumulation of retinoids in the liver; retinoid-induced hepatocellular damage; the spillage of stored retinoids into the circulation; and the transport of these compounds to the gut and brain in toxic concentrations. The retinoid hypothesis could be tested clinically by comparing cases of mefloquine toxicity and untreated controls in terms of retinoid profiles (retinol, retinyl esters, percent retinyl esters, and retinoic acid). Subject to such tests, retinoid profiling could provide an indicator for assessing mefloquine-associated adverse effects.


Subject(s)
Aggression/drug effects , Chemical and Drug Induced Liver Injury/complications , Hypervitaminosis A/etiology , Liver/metabolism , Mefloquine/adverse effects , Psychoses, Substance-Induced/etiology , Retinoids/metabolism , Chemical and Drug Induced Liver Injury/metabolism , Humans , Hypervitaminosis A/complications , Malaria/drug therapy , Mefloquine/therapeutic use , Models, Biological , Oxidoreductases/antagonists & inhibitors , Retinoids/blood
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