Increased serum phosphate levels and calcium fluxes are seen in smaller individuals after a single dose of sodium phosphate colon cleansing solution: a pharmacokinetic analysis.
BACKGROUND
Sodium phosphate containing colonoscopy preparations may cause electrolyte disturbances and calcium-phosphate nephropathy. Decreased body weight is an unexplored risk factor for complications with sodium phosphate ingestion.


OBJECTIVE
To perform a pharmacokinetic analysis of a single dose of Fleet Phospho-Soda in smaller and larger individuals.


METHODS
Seven subjects weighing <55 kg (Group I) and six weighing >100 kg (Group II) consumed 45 mL Fleet Phospho-Soda. Serum electrolytes were measured. Hydration was closely maintained by monitoring weight, fluid intake and total body water.


RESULTS
Marked increases in serum phosphate were seen in Group I compared to Group II. For example, mean serum phosphate at 120 min was 7.8 +/- 0.5 mg/dL in Group I and 5.1 +/- 0.8 mg/dL in Group II (P < 0.001). Normalized area under the phosphate vs. time curve for Group I was 1120 +/- 190 mg/dL*min and 685 +/- 136 mg/dL*min for Group II (P < 0.001). Twelve-hour urine calcium was lower in Group I (16.4 +/- 7.6 mg) than in Group II (39.2 +/- 7.8 mg, P < 0.001).


CONCLUSIONS
Increased serum phosphate occurs in smaller individuals after ingestion of sodium phosphate preparations, even with strict attention to fluid intake. Smaller body weight poses a potential risk for calcium-phosphate nephropathy.
Ehrenpreis
E D
ED
Department of Gastroenterology, Highland Park Hospital, NorthShore University HealthSystem, Highland Park, IL 60035, USA. ehrenpreis@gipharm.net
D000328:Adult; D001823:Body Composition; D002130:Calcium Phosphates / Q000493:pharmacokinetics*; D002400:Cathartics / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003113:Colonoscopy; D004573:Electrolytes / Q000097:blood / Q000378:metabolism; D005260:Female; D006801:Humans; D054559:Hyperphosphatemia / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000097:blood* / Q000493:pharmacokinetics; D012307:Risk Factors; D007507:Therapeutic Irrigation / Q000379:methods; D015431:Weight Loss
D002130:Calcium Phosphates; D002400:Cathartics; D004573:Electrolytes; D010710:Phosphates; C018279:sodium phosphate