MICRO-K LS
Clinical safety rating
cautionComprehensive clinical and safety monograph for MICRO-K LS (MICRO-K LS).
Potassium supplement; replaces intracellular potassium, essential for nerve conduction, muscle contraction, and acid-base balance.
| Metabolism | Not metabolized; excreted primarily via kidneys. |
| Excretion | Renal: ~90% as KCl (proportional to intake). Biliary/fecal: <10%. |
| Half-life | Not applicable (K+ is an electrolyte, not eliminated by first-order kinetics). Clinical context: Serum K+ decline follows redistribution and excretion with a half-life of ~2-4 hours after IV bolus. |
| Protein binding | None (K+ is free ion). |
| Volume of Distribution | 0.35 L/kg (approximate total body water; distributes primarily in extracellular fluid). |
| Bioavailability | Oral: ~80-100% for microencapsulated KCl (MICRO-K), but can be incomplete due to slower release. |
| Onset of Action | Oral: 30-60 minutes for serum K+ increase. IV: Immediate. |
| Duration of Action | Oral: Maintains K+ levels for 6-12 hours (dose-dependent). IV: Effect sustained only during infusion. |
| Molecular Weight | 74.55 |
10-20 mEq (as potassium chloride) orally twice daily; maximum 100 mEq/day.
| Dosage form | FOR SUSPENSION, EXTENDED RELEASE |
| Renal impairment | GFR 50-90 mL/min: no adjustment. GFR 30-49 mL/min: reduce dose by 25-50%. GFR <30 mL/min: avoid use or reduce dose by 50-75% with close monitoring. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 25-50%. Child-Pugh C: avoid use or reduce dose by 50%. |
| Pediatric use | 1-3 mEq/kg/day orally in 2-4 divided doses; maximum 1 mEq/kg per dose and 100 mEq/day. |
| Geriatric use | Initiate at lower end of dosing range (10-20 mEq/day); monitor renal function and serum potassium frequently; adjust based on renal function. |
| 1st trimester | Potassium chloride is generally avoided in the first trimester unless necessary for maternal benefit, as hypokalemia can be harmful. There are no well-controlled studies, but no significant teratogenicity has been reported. |
| 2nd trimester | Use with caution during the second trimester. Potassium supplementation should be based on maternal need, with monitoring of serum potassium levels. |
| 3rd trimester | Use with caution during the third trimester. Hypokalemia may be associated with adverse pregnancy outcomes; however, excessive potassium can cause maternal hyperkalemia, which may affect the fetus. Close monitoring is required. |
Clinical note
Comprehensive clinical and safety monograph for MICRO-K LS (MICRO-K LS).
| Placental transfer | Potassium readily crosses the placenta. Fetal serum potassium levels are approximately 0.5 mEq/L higher than maternal levels due to active transport. |
| Breastfeeding | Potassium chloride passes into breast milk in small amounts. It is considered compatible with breastfeeding as it is a normal milk component; however, the potential for infant electrolyte imbalance should be considered, especially with high maternal doses. |
| Lactation Rating | L1 (Compatible) |
| Teratogenic Risk | MICRO-K LS (potassium chloride) is not associated with teratogenicity. No fetal risks have been reported in any trimester. Use during pregnancy is considered safe when indicated. |
| Fetal Monitoring | Monitor serum potassium levels periodically, especially in renal impairment or concomitant medications affecting potassium. No specific fetal monitoring required. |
| Fertility Effects | No known effects on fertility. Potassium chloride is a normal electrolyte; therapeutic use does not impair reproductive function. |
■ FDA Black Box Warning
No black box warning.
| Serious Effects |
Hyperkalemia (serum potassium >5.5 mEq/L)Severe renal impairment (creatinine clearance <30 mL/min)Untreated Addison's diseaseAcute dehydrationExtensive tissue breakdown (e.g., severe burns, crush injuries)
| Precautions | Risk of hyperkalemia especially in renal impairment, Use with caution in cardiac disease, GI irritation or ulceration with oral forms, Slow release formulations may cause GI lesions |
| Food/Dietary | Avoid excessive intake of potassium-rich foods (e.g., bananas, oranges, potatoes, spinach, avocados, dried fruits, salt substitutes containing potassium chloride). Do not take with alcohol as it may increase GI irritation. Grapefruit juice has no significant interaction, but large amounts of any food high in potassium should be avoided. |
| Clinical Pearls | MICRO-K LS contains potassium chloride microencapsulated granules for sustained release. Avoid in patients with severe renal impairment (CrCl <30 mL/min), untreated Addison's disease, or hyperkalemia. Use with caution in patients with cardiac disease or concurrent use of ACE inhibitors, ARBs, or potassium-sparing diuretics. Do not crush or chew capsules; administer with a full glass of water to prevent GI mucosal damage. Monitor serum potassium regularly, especially in elderly and diabetic patients. |
| Patient Advice | Take this medication exactly as prescribed, preferably with meals or a full glass of water. · Do not crush, chew, or break the capsules; swallow them whole. · Avoid foods high in potassium (e.g., bananas, oranges, tomatoes, salt substitutes) unless directed by your doctor. · Contact your doctor immediately if you experience muscle weakness, irregular heartbeat, numbness/tingling, or dark/tarry stools. · Store at room temperature away from moisture and heat. |
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