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Cureus Jan 2023Methemoglobinemia is a condition caused by increased methemoglobin, a reduced form of hemoglobin, in the blood. This causes the molecules to bind oxygen more tightly and...
Methemoglobinemia is a condition caused by increased methemoglobin, a reduced form of hemoglobin, in the blood. This causes the molecules to bind oxygen more tightly and decreases their ability to release that oxygen to tissue. Most cases of methemoglobinemia are acquired and occur either in pediatric populations or in individuals with predisposing conditions. This report illustrates a case of an otherwise healthy 31-year-old patient presenting to the emergency department with cyanosis of the hands and mouth and an O2 saturation of 78% after taking increased doses of the over-the-counter medication phenazopyridine. A "chocolate-brown" color of her arterial blood, and increased methemoglobin levels of 20.2%, confirmed the diagnosis of methemoglobinemia. She was treated with both methylene blue and ascorbic acid, and her oxygen saturation and serum chemistry returned to normal levels within a few hours. The case highlights the importance of discussing the dosage of all over-the-counter medications with patients and recognizing the signs and symptoms of methemoglobinemia.
PubMed: 36788851
DOI: 10.7759/cureus.33715 -
European Journal of Pharmacology Mar 2023and purpose: Phenazopyridine (PAP) is an over-the-counter drug widely used to provide symptomatic relief of bladder pain in conditions such as cystitis or bladder pain...
BACKGROUND
and purpose: Phenazopyridine (PAP) is an over-the-counter drug widely used to provide symptomatic relief of bladder pain in conditions such as cystitis or bladder pain syndrome (BPS). Whereas the analgesic effect of PAP has been attributed to a local effect on the mucosa of the lower urinary tract (LUT), the molecular targets of PAP remain unknown. We investigated the effect of PAP on pain-related Transient Receptor Potential (TRP) channels expressed in sensory neurons that innervate the bladder wall.
EXPERIMENTAL APPROACH
The effects of PAP on the relevant TRP channels (TRPV1, TRPA1, TRPM8, TRPM3) expressed in HEK293 or CHO cells was investigated using Fura-2-based calcium measurements and whole-cell patch-clamp recordings. Activity of PAP on TRPM8 was further analysed using Fura-2-based calcium imaging on sensory neurons isolated from lumbosacral dorsal root ganglia (DRG) of mice.
KEY RESULTS
PAP rapidly and reversibly inhibits responses of TRPM8 expressed in HEK293 cells to cold and menthol, with IC values between 2 and 10 μM. It acts by shifting the voltage dependence of channel activation towards positive potentials, opposite to the effect of menthol. PAP also inhibits TRPM8-mediated, menthol-evoked calcium responses in lumbosacral DRG neurons. At a concentration of 10 μM, PAP did not significantly affect TRPA1, TRPV1, or TRPM3.
CONCLUSION AND IMPLICATIONS
PAP inhibits TRPM8 in a concentration range consistent with PAP levels in the urine of treated patients. Since TRPM8 is expressed in bladder afferent neurons and upregulated in patients with painful bladder disorders, TRPM8 inhibition may underlie the analgesic activity of PAP.
Topics: Animals; Cricetinae; Humans; Mice; Calcium; Cricetulus; Fura-2; Ganglia, Spinal; HEK293 Cells; Menthol; Pain; Phenazopyridine; Sensory Receptor Cells; Transient Receptor Potential Channels; TRPA1 Cation Channel; TRPM Cation Channels; Urinary Bladder
PubMed: 36657655
DOI: 10.1016/j.ejphar.2023.175512 -
European Urology Focus Jul 2023The rise in antimicrobial resistance means that alternative approaches for the treatment and prevention of urinary tract infection (UTIs) are required. (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
The rise in antimicrobial resistance means that alternative approaches for the treatment and prevention of urinary tract infection (UTIs) are required.
OBJECTIVE
To evaluate the safety and efficacy of a D-mannose-based dietary supplement (D-mannose, citric acid, prebiotic fibers, Astragalus, and dandelion; DAPAD complex) for the treatment of uncomplicated acute E. coli UTIs.
DESIGN, SETTING, AND PARTICIPANTS
This was a single-center, randomized, double-blind, placebo-controlled trial conducted from April 2021 to October 2021 in Rajalakshmi Hospital and Research Centre (Bangalore, India). The participants were nonmenopausal women with an acute uncomplicated E. coli UTI. UTI was diagnosed according to the presence of at least one urinary symptom and bacteriuria (>100 000 CFU/ml).
INTERVENTION
The DAPAD complex was administered twice a day for 5 d, with phenazopyridine and alkalizing agents as the standard of care (SOC). The control group received placebo with SOC.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS
Subjective (clinical resolution/response) and objective (midstream bacteriuria) outcomes were evaluated at the end of therapy (day 6) and at day 35 of follow-up. Adverse events were recorded. Categorical variables were analyzed using χ and Fisher's exact tests; a p value <0.05 was considered significant.
RESULTS AND LIMITATIONS
Seventy women were enrolled and equally randomized to the two groups. Clinical resolution was higher in the DAPAD group at 6 d (34.3% vs 0%; p < 0.0001) and 35 d from baseline (88.6% vs 20%, p < 0.0001). At day 35, no patients in the DAPAD group had moderate or severe symptoms, whereas 25.7% (nine/35) and 11.4% (four/35) of patients in the placebo group had moderate and severe symptoms, respectively. Bacteriological resolution was also higher in the DAPAD group at day 6 (85.7% vs 14.3%; p < 0.0001) and day 35 (100% vs 40%; p < 0.0001). Three mild adverse events (4.26%) unrelated to the investigated product were recorded, all of which were medically treated.
CONCLUSIONS
The DAPAD complex dietary supplement is effective and safe for treatment of acute uncomplicated E. coli UTIs.
PATIENT SUMMARY
Our results show that for nonmenopausal women with an uncomplicated Escherichia coli urinary tract infection, those treated with a dietary supplement (containing D-mannose, citric acid, prebiotic fibers, Astragalus, and dandelion) had a higher rate of clinical resolution or response than women who received a placebo.
Topics: Female; Humans; Mannose; Bacteriuria; Escherichia coli; Treatment Outcome; India; Urinary Tract Infections; Escherichia coli Infections; Dietary Supplements; Prebiotics
PubMed: 36621376
DOI: 10.1016/j.euf.2022.12.013 -
Clinics and Practice Oct 2022Methemoglobinemia is a rare blood disorder characterized by the oxidation of heme iron from ferrous (Fe) to ferric (Fe) state, which increases oxygen affinity and...
Methemoglobinemia is a rare blood disorder characterized by the oxidation of heme iron from ferrous (Fe) to ferric (Fe) state, which increases oxygen affinity and impairs oxygen release to the tissue causing hypoxia. It can be congenital or acquired; however, most cases are acquired and caused by exogenous substances such as medications, chemicals, and environmental substances. Phenazopyridine is an over-the-counter urinary analgesic medication commonly used for symptomatic relief of dysuria and has been reported to cause methemoglobinemia. However, only a handful of cases of phenazopyridine-induced methemoglobinemia have been reported. We present a case of an 89-year-old female who presented with severe hypoxia, shortness of breath, headache, nausea, and dizziness caused by phenazopyridine-induced methemoglobinemia. She was found to have a methemoglobin level of 21.5% and was treated with methylene blue, leading to a rapid improvement of her symptoms. She was taking one over-the-counter phenazopyridine 200 mg tablet three times daily for two weeks for her chronic dysuria. This case highlights the need to have a high index of suspicion of phenazopyridine-induced methemoglobinemia in a patient presenting with unexplained shortness of breath with a history of phenazopyridine use as it could lead to severe methemoglobinemia with hypoxia that could potentially be fatal if not promptly diagnosed.
PubMed: 36412668
DOI: 10.3390/clinpract12060089 -
Neuropsychopharmacology : Official... Nov 2022Alzheimer's disease (AD) is the most common form of dementia with no effective treatment options. A complete elucidation of its underlying molecular mechanisms,...
Alzheimer's disease (AD) is the most common form of dementia with no effective treatment options. A complete elucidation of its underlying molecular mechanisms, including the transcription regulation of genes critically involved in AD, may shed light on new therapeutic development. RPS23RG1 is a newly identified AD-associated gene, whose expression is decreased in AD and restoration can attenuate AD-like phenotypes in animal models. However, the transcription regulation of RPS23RG1 remains unknown. In this study, we explored the promoter of RPS23RG1 and identified its transcription initiation site (TSS) at 1525 bp upstream of the ATG translation start codon. Progressive deletion analysis determined the presence of a negative regulatory region and a positive regulatory region within nucleotide positions +1127 to +1187 and +732 to +1127 relative to the TSS (+1), respectively. We conducted a reporter system to screen for compounds that increase RPS23RG1 expression through antagonizing its negative regulatory elements and identified phenazopyridine. Importantly, we demonstrated that phenazopyridine not only promoted RPS23RG1/Rps23rg1 expression, but also reduced AD-like pathologies and cognitive impairments in the APP/PS1 AD model mice. We also determined a critical negative regulatory domain of RPS23RG1 within nucleotide positions +1177 to +1187 and found that the transcription factor SMAD3 bound to this domain. Inhibition of SMAD3 promoted RPS23RG1 expression. Moreover, phenazopyridine reduced SMAD3 binding to the RPS23RG1 promoter without affecting SMAD3 phosphorylation and nuclear localization. Taken together, our results determine the transcription regulation mechanism of RPS23RG1 and show that phenazopyridine has potential for AD treatment through regulating RPS23RG1 transcription.
Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Codon, Initiator; Disease Models, Animal; Mice; Mice, Transgenic; Nucleotides; Phenazopyridine; Phenotype; Transcription Factors
PubMed: 35821069
DOI: 10.1038/s41386-022-01373-7 -
Clinical Practice and Cases in... May 2022As ketamine gains traction as an alternative to opiates in the treatment of chronic pain, ketamine-induced ulcerative cystitis is now being recognized as a complication...
INTRODUCTION
As ketamine gains traction as an alternative to opiates in the treatment of chronic pain, ketamine-induced ulcerative cystitis is now being recognized as a complication of its use. The first-line treatment is phenazopyridine, an over-the-counter medication for dysuria that historically has been known to cause methemoglobinemia. This report details the case of a patient presenting to the emergency department (ED) with methemoglobinemia.
CASE REPORT
A 66-year-old woman with a complicated medical history presented to the ED with anemia and hypoxia after extended use of phenazopyridine for treatment of ketamine-induced ulcerative cystitis. She was found to have methemoglobinemia secondary to phenazopyridine used to treat her ketamine-induced ulcerative cystitis, a previously undocumented sequelae of chronic ketamine use. She was admitted to the hospital for three days and made a full recovery.
CONCLUSION
This case highlights the need to suspect ketamine-induced ulcerative cystitis in patients who use ketamine chronically and be judicious in the use of phenazopyridine for symptom management to prevent life-threatening complications.
PubMed: 35701344
DOI: 10.5811/cpcem.2022.1.55277 -
International Journal of Women's Health 2022To assess patient reliance on various over-the-counter (OTC) modalities used for prevention of recurrent urinary tract infection (RUTI) after electrofulguration (EF).
PURPOSE
To assess patient reliance on various over-the-counter (OTC) modalities used for prevention of recurrent urinary tract infection (RUTI) after electrofulguration (EF).
PATIENTS AND METHODS
Following IRB approval, qualifying women were offered a short survey over the phone by a medical researcher to collect information about their use of various OTC modalities for prophylaxis of RUTI. Data was compared between two cohorts, ≥70 years old and <70 years old, using chi-squared and Student's -tests.
RESULTS
From a database of 324 patients, 163 accepted the interview. 17% (28/163) reported current use of cranberry supplements, 10% (16/163) D-mannose supplements, and 42% (69/163) another non-prescription modality for RUTI prophylaxis. The non-geriatric (<70 years old) cohort spent, on average, $80 less annually on cranberry/D-mannose supplements (=0.043) than the geriatric cohort and were more likely to use non-prescription modalities for the prevention of UTI (52% vs 30%; =0.0061). Individuals using D-mannose were also much more likely to purchase their product online compared to those using cranberry supplements (85% vs 56%). Across all modalities, the perceived benefit difference in reducing UTI/year ranged from a median of 0 for Pyridium® (phenazopyridine hydrochloride) to four for probiotics, with D-mannose and cranberry at two/year, and those increasing daily fluid consumption at 2.5 fewer UTI/year.
CONCLUSION
Continued use of non-prescription modalities for RUTI prophylaxis were common among women with an EF history, but varied based on age groups. Across both age cohorts, annual expenditure and perceived benefit also varied among different OTC prophylactic modalities. Awareness of type and method of OTC modality implementation by patients with RUTI is essential to aligning use with current field recommendations.
PubMed: 35535150
DOI: 10.2147/IJWH.S355469 -
European Journal of Case Reports in... 2022Phenazopyridine is an over-the-counter urinary analgesic commonly used to alleviate the burning and urgency associated with lower urinary tract infections....
INTRODUCTION
Phenazopyridine is an over-the-counter urinary analgesic commonly used to alleviate the burning and urgency associated with lower urinary tract infections. Methaemoglobinaemia is an uncommon adverse effect of phenazopyridine use. We report a case of methaemoglobinaemia in a patient prescribed daily phenazopyridine to treat urethral and bladder irritation caused by a chronic indwelling Foley catheter.
CASE DESCRIPTION
A 55-year-old female resident of a long-term acute care facility with a chronic Foley, tracheostomy and ventilator-dependent respiratory failure was observed to have generalized dusky skin and hypoxia. Pulse oximetry was reading in the high 80s despite administration of 100% FiO2. ABG revealed paO2 of 451, oxyhaemoglobin level 75% and methaemoglobin level 22%. Medication review indicated that the patient was prescribed phenazopyridine 400 mg TID for the previous 2 months. This medication was discontinued. Considering she was chronically taking mirtazapine, she can increase risk of serotonin syndrome should she be administered first-line treatment with methylene blue. Vitamin C was thus instead administered as a second-line agent. Serial ABGs showed a rapid decline in methaemoglobin levels and an increase in oxyhaemoglobin within 2 days.
DISCUSSION
Acquired methaemoglobinaemia is a rare adverse effect of treatment with phenazopyridine. This risk increases when drug dosage and duration exceed manufacturer specifications. Treatment typically includes cessation of the offending drug and administration of methylene blue in severe cases. A thorough medication reconciliation should be performed prior to methylene blue initiation, as patients taking serotonergic medications (for example, MAOIs, SSRIs, SNRIs, TCAs) are at increased risk of serotonin toxicity with co-administration of methylene blue. In these instances, ascorbic acid/vitamin C can be chosen as an alternative treatment agent.
CONCLUSION
Work-up of refractory hypoxia should involve a thorough review of medications as even some over-the-counter drugs can cause the fatal side effect of methaemoglobinaemia. Treatment with vitamin C should be considered over methylene blue if serotonergic medications have been recently prescribed in order to avoid risk of serotonin syndrome.
LEARNING POINTS
Methaemoglobinaemia is an uncommon, life-threatening adverse effect of phenazopyridine use. Presentation depends on the severity of the disorder, ranging from headache, weakness, lightheadedness and dyspnoea, to arrhythmias, confusion, seizures and multiorgan failure.Workup of refractory hypoxia should involve a comprehensive medication review as even some over-the-counter drugs can cause methaemoglobinaemia.Management of methaemoglobinaemia involves cessation of the offending drug, administration of supplemental oxygen and treatment with methylene blue (1-2 mg/kg) if MetHb >30%, or for symptomatic patients with MetHb >20%. Vitamin C can be used as an alternative agent if there is a contraindication to methylene blue (for example, with patients simultaneously receiving serotonergic medications and/or those with G6PD deficiency).
PubMed: 35265556
DOI: 10.12890/2022_003191 -
Asia Pacific Allergy Jan 2022Delayed hypersensitivity reaction of penicillin is commonly seen, but never reported in pyridium. This case illustrates a patient with delayed hypersensitivity reaction...
Delayed hypersensitivity reaction of penicillin is commonly seen, but never reported in pyridium. This case illustrates a patient with delayed hypersensitivity reaction after the use of augmentin and pyridium. Skin patch test, surprisingly, confirmed pyridium delayed hypersensitivity.
PubMed: 35174061
DOI: 10.5415/apallergy.2022.12.e10