XYLOSE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for XYLOSE (XYLOSE).
Xylose is a pentose sugar that is absorbed in the small intestine via passive diffusion and active transport. It is used to assess intestinal mucosal integrity; its absorption reflects the function of the enterocytes. After absorption, it is not metabolized and is excreted unchanged in urine, making it a marker for intestinal absorption and renal function.
| Metabolism | Xylose is not significantly metabolized in humans; it is excreted unchanged primarily by the kidneys via glomerular filtration. |
| Excretion | Renal: approximately 85-90% eliminated unchanged in urine; biliary/fecal: negligible (<5%). |
| Half-life | Terminal elimination half-life: 1.2-2.5 hours in adults with normal renal function; prolonged in renal impairment (up to 10 hours). |
| Protein binding | <5% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | 0.2-0.3 L/kg; indicates distribution primarily in extracellular fluid. |
| Bioavailability | Oral: 30-50% (due to first-pass metabolism and incomplete absorption); intravenous: 100%. |
| Onset of Action | Oral: onset of action within 30 minutes; peak effect at 1-2 hours. Intravenous: immediate onset. |
| Duration of Action | Duration: 2-4 hours for diagnostic effects (D-xylose absorption test); prolonged in malabsorption states. |
| Molecular Weight | 150.13 |
Adults: 25 g orally in 500 mL water, administered as a single dose for D-xylose absorption test.
| Dosage form | POWDER |
| Renal impairment | No specific dose adjustment guidelines; caution in severe renal impairment due to potential accumulation if used systemically (not typical). |
| Liver impairment | No specific adjustments for Child-Pugh class. |
| Pediatric use | Pediatric: 0.5 g/kg body weight (max 25 g) orally in 200-500 mL water, given as a single dose. |
| Geriatric use | No specific adjustment required; use same dosing as adults, monitor for adequate hydration. |
| 1st trimester | No known teratogenic effects; limited human data; use with caution. |
| 2nd trimester | No known fetal risks; limited human data. |
| 3rd trimester | No known fetal risks; limited human data. |
Clinical note
Comprehensive clinical and safety monograph for XYLOSE (XYLOSE).
| Placental transfer | Limited data; likely crosses placenta due to low molecular weight. |
| Breastfeeding | Excretion into breast milk unknown; unlikely to cause harm due to low systemic absorption. However, caution advised. |
| Lactation Rating | L3 (Moderately Safe) |
■ FDA Black Box Warning
No FDA black box warnings.
| Serious Effects |
Hypersensitivity to xyloseSevere renal impairment
| Precautions | Use with caution in patients with renal impairment (may affect excretion and test interpretation), dehydration, or ascites. False-positive results may occur in patients with decreased renal function. Ensure adequate hydration during the test. |
| Food/Dietary | Avoid food and beverages (except water) for 8-12 hours before and 2 hours after the D-xylose dose. Do not consume high-fiber foods, as they may interfere with absorption. |
| Clinical Pearls |
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| Teratogenic Risk | Xylose is a naturally occurring sugar and is generally considered to have low teratogenic potential. There are no well-controlled studies in pregnant women; animal studies have not reported fetal harm. First trimester: unlikely to cause major malformations. Second and third trimesters: no known adverse fetal effects. Use with caution only if clearly needed. |
| Fetal Monitoring | Monitor maternal renal function and glucose levels if xylose is used in renal function tests. No specific fetal monitoring required; standard prenatal care is adequate. |
| Fertility Effects | No known effects on fertility in animal studies. Insufficient human data to determine impact on fertility. |
| Xylose is a diagnostic sugar used for the D-xylose absorption test to evaluate intestinal malabsorption. Administer 25 g of D-xylose orally, then measure serum levels at 1 hour (normal >25 mg/dL) and 5-hour urine collection (normal >4 g). Low levels suggest mucosal disease; normal levels suggest pancreatic insufficiency. False positives occur with renal impairment, delayed gastric emptying, or incomplete urine collection. |
| Patient Advice | Take the medication exactly as prescribed with an empty stomach, fasting for 8-12 hours before the test. · After taking Xylose, you may drink only water for the next 2 hours. · Report any nausea, bloating, or diarrhea, which are common side effects. · Collect all urine for 5 hours after the dose; missing sample invalidates the test. · Inform your doctor if you have kidney disease, liver disease, or diabetes. |