Magnesium Citrate
Magnesium citrate is an oral saline cathartic used infrequently in veterinary medicine. Its principal role is bowel evacuation in selected constipated patients or before certain procedures. The cathartic action depends on magnesium-containing solute remaining within the intestine. It is a different compound from magnesium carbonate used in some phosphate-binding supplements.
Group
Saline cathartic
Mechanism of Action
Poorly absorbed magnesium and associated solutes increase osmotic activity within the intestinal lumen and retain water. Fluid accumulation softens intestinal contents and produces distension, which can stimulate motility and evacuation. The cathartic effect depends on luminal exposure; any absorbed magnesium enters systemic magnesium handling rather than contributing directly to the bowel-emptying action.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Bowel evacuation | 120–240 mg/kg | PO | Every 24 h | Mass equivalent of 2-4 mL/kg/day of a 6% solution; not an elemental-magnesium dose. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Bowel evacuation | 120–240 mg/kg | PO | Every 24 h | Mass equivalent of 2-4 mL/kg/day of a 6% solution; not an elemental-magnesium dose. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Bowel evacuation | 120–240 mg/kg | PO | Once | Mass equivalent of 2-4 mL/kg once of a 6% solution. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Bowel evacuation | 120–240 mg/kg | PO | Once | Mass equivalent of 2-4 mL/kg once of a 6% solution. |
Indications
- Cathartic treatment of selected constipation in veterinary patients.
- Bowel evacuation before selected diagnostic or surgical procedures when an osmotic cathartic is appropriate.
Contraindications
- Renal impairment can cause magnesium accumulation.
- Correct dehydration before cathartic use.
- Avoid cathartic use during dehydration; repeated use can cause major fluid/electrolyte disturbance.
Interactions
- Magnesium can chelate oral fluoroquinolones and reduce their absorption.
- Rapid transit may alter uptake of other oral drugs.
Adverse effects
- Fluid and electrolyte loss
- Hypermagnesaemia with impaired excretion
Toxicity
Stop administration and assess electrolytes and renal function if weakness or excessive catharsis develops.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Magnesium citrate 6% oral liquid | Oral Liquid | 6 g / 100 mL | PO |
Monitoring and Administration
Monitor hydration and magnesium after repeated or high doses.
Pronefra contains magnesium carbonate rather than magnesium citrate; do not treat it as a citrate preparation.
Store magnesium citrate solution at 2-30°C. The hyperosmotic-laxative chapter adds storage/safety information but no additional citrate-specific numerical veterinary dose.