ACQUIRED FANCONI SYNDROME FOLLOWING DEGRADED TETRACYCLINE

Acquired disorders of phosphaturia: Beyond tumor-induced osteomalacia

Phosphate is an integral part of human cellular structure and function. Though most recognised disorders of phosphaturia are genetic in origin, phosphate loss due to acquired conditions is commonly encountered in clinical practice. Acquired hypophosphatemia is most commonly due to renal phosphate wasting and can produce significant morbidity. It also heralds future kidney damage, and continued exposure can lead to progressive kidney injury and potentially renal failure. These conditions are a diverse group of disorders with common shared mechanisms causing loss of phosphate in the urine. Renal phosphate loss can occur as an isolated entity or as a part of generalised proximal tubular dysfunction, i.e., Fanconi's syndrome. An insight into the pathophysiological mechanisms of acquired phosphaturia can help clinicians monitor their patients better and avoid potential harms.

Developmental toxicity and transcriptome analysis of 4-epianhydrotetracycline to zebrafish (Danio rerio) embryos

As a primary degradation by-product of tetracycline (TC), 4-Epianhydrotetracycline (4-EATC) has been detected frequently in the aquatic environment, which may pose a potential environmental risk to aquatic organisms. Up to now, however, the toxicology study on 4-EATC to aquatic organisms is limited. In the present study, in order to better understand the toxic mechanism of 4-EATC, developmental toxicity including lethal and sublethal effects of 4-EATC and TC were investigated. The results showed that the developmental toxicity of 4-EATC to zebrafish embryos was stronger than that of TC. The 96 h LC₅₀ value of 4-EATC to zebrafish embryos was 29.13 mg/L. Malformations seemed to be the most sensitive sublethal endpoint of 4-EATC exposure, and the 96 h EC₅₀ value was 8.57 mg/L. Transcriptome response of 4-EATC to zebrafish embryos was determined. The results showed that 430 different expression genes (DEGs) caused by 4-EATC, and most enriched in tryptophan (TRP) metabolism pathway. Annotation of DEGs in the TRP metabolism demonstrated that expression of 4 gene products in tryptophan metabolized along the kynurenine (KYN) pathway were changed. Disorder of TRP catabolism in KYN pathway was a potential mechanism of 4-EATC toxicity to zebrafish embryos.

Adefovir dipivoxil-induced Fanconi syndrome and its predictive factors: A study of 28 cases

The aim of the present study was to identify monitoring and prevention measures as well as predictive factors for early detection of renal toxicity associated with long-term administration of adefovir dipivoxil in order to avoid progression to Fanconi syndrome. Clinical data of 28 patients with Fanconi syndrome caused by long-term administration of adefovir dipivoxil for the treatment of chronic hepatitis B virus (HBV) infection were collected pre-and post-administration for analysis. Patients presented with fatigue, progressive systemic pain in multiple bones and joints, as well as difficulty in walking and pathological fractures in a number of severe cases. Laboratory examinations revealed hypophosphatemia, elevated serum cystatin C (Cys-C), elevated serum creatinine (SCr), reduced glomerular filtration rate (GFR), positive urinary protein, erythrocytes and glucose, as well as osteoporosis. In consequence, adefovir dipivoxil administration was stopped, and patients received concentrated divitamins, sodium phosphate syrup and calcitriol. Symptoms and abnormalities in laboratory examinations were significantly improved in all patients after 2-6 months. Therefore, serum phosphate, SCr, routine urine parameters, Cys-C and GFR should be monitored regularly in chronic HBV patients treated with adefovir dipivoxil. The following factors were identified as predictive of kidney damage and Fanconi syndrome: Age ≥40 years, living in rural areas, previous renal toxicity, estimated GFR (eGFR) <90 ml/min/1.73 m², hypertension, diabetes, cirrhosis and duration of adefovir dipivoxil treatment exceeding 24 months. The present results indicate that timely termination of adefovir dipivoxil treatment and replacement with other antiviral agents is critical once renal impairment appears, and that it is necessary to change to other antiviral agents and prolong the interval of administration according to the eGFR level.

Identification and characterization of stressed degradation products of rabeprazole using LC-ESI/MS/MS and 1H-NMR experiments: in vitro toxicity evaluation of major degradation products

Rabeprazole, an antiulcer drug in the class of proton pump inhibitors was subjected to force degradation studies as per ICH guidelines Q1A (R2).

Drug-Induced Metabolic Acidosis

Metabolic acidosis could emerge from diseases disrupting acid-base equilibrium or from drugs that induce similar derangements. Occurrences are usually accompanied by comorbid conditions of drug-induced metabolic acidosis, and clinical outcomes may range from mild to fatal. It is imperative that clinicians not only are fully aware of the list of drugs that may lead to metabolic acidosis but also understand the underlying pathogenic mechanisms. In this review, we categorized drug-induced metabolic acidosis in terms of pathophysiological mechanisms, as well as individual drugs’ characteristics.

Acquired Fanconi syndrome in a dog exposed to jerky treats in Japan

A 6-year-old spayed female Jack Russell Terrier presented with a 1-month history of lethargy, anorexia, vomiting and weight loss. The dog was fed beef and chicken jerky treats daily in addition to a commercial diet. Laboratory tests revealed azotemia, hypokalemia, hyperchloremia, metabolic acidosis and glucosuria with normoglycemia. Urine amino acid analysis showed significant amino acid loss into the urine. Thus, Fanconi syndrome was diagnosed, and based on the case history and extensive diagnostic testing, excessive consumption of jerky treats was strongly suspected as the cause. Glucosuria resolved 7 days after the withdrawal of jerky treats and fluid therapy. Aminoaciduria was substantially, but not completely, improved 3 months after diagnosis. Mild azotemia remained, suggesting chronic renal disease. To the best of our knowledge, this is the first reported case of Fanconi syndrome following the consumption of jerky treats in Japan.

Proximal renal tubular acidosis in methylmalonic acidemia

A patient with methylmalonic acidemia was found to have a persistent hyperchloremic acidosis. Investigation documented the presence of a proximal renal tubular acidosis. Between 14 and 18 months of age the urinary pH was as high as 8.0 when the serum bicarbonate was 17 mEq/liter and the threshold for bicarbonate was at 16-17 mEq/liter. When restudied at 33 months of age, the threshold had risen to 20 mEq/liter, but this was still abnormal and supplemental treatment was required to keep the serum concentration of bicarbonate above 20 mEq/liter. It is postulated that organic acid metabolites which accumulate in this and related disorders may interfere with renal tubular function as has been shown for maleic acid in experimental animals.

Halitosis: an etiologic classification, a treatment approach, and prevention

Halitosis, a condition that causes a severe social handicap to those who suffer from it, has a multifactorial etiology. Since patients with this condition seek professional consultation from dentists much more frequently than from physicians, dentists, who treat diseases of the oral cavity, should have an understanding of the local as well as the systemic factors which cause halitosis. This article presents an extensive review of the information available, with an etiologic classification of this condition to help clinicians develop the diagnostic acumen to distinguish one type of halitosis from another. Once the etiology of this condition is ascertained for the patient who suffers from it, treatment can be readily rendered.

Fanconi syndrome associated with cephalothin and gentamicin therapy

A case is reported of Fanconi syndrome and nonliquric renal failure, following a brief course of cephalothin and gentamicin, in a patient with diffuse histiocytic lymphoma. These drugs, especially when used in combination, have been associated with nephrotoxicity manifested as acute tubular necrosis and altered proximal tubular function, but biochemical evidence for generalized proximal tubular dysfunction has not been accurately defined. Thus far, only two other antibiotics, degraded tetracycline and streptozotocin, have been implicated in producing an acquired Fanconi syndrome.