K+8
Clinical safety rating: caution
Comprehensive clinical and safety monograph for K+8 (K+8).
Potassium ion replenishment; corrects hypokalemia by increasing extracellular potassium concentration, restoring membrane potential and cardiac conduction.
| Metabolism | Not metabolized; primarily excreted unchanged by the kidneys via distal tubular secretion. |
| Excretion | Primarily renal: >90% excreted unchanged by kidneys. Minor fecal (<5%) and negligible biliary elimination. |
| Half-life | Terminal elimination half-life ~2-4 hours (shorter with valproate coadministration, prolonged with renal impairment). |
| Protein binding | <10% bound; primarily to albumin. Binding is negligible. |
| Volume of Distribution | 0.3-0.4 L/kg (adults); Vd decreases in neonates and increases in pregnancy. |
| Bioavailability | Oral immediate-release: 85-95%; extended-release: 80-90% (dependent on formulation). IV: 100%. |
| Onset of Action | Oral: 1-2 hours (tablets/capsules); Extended-release: 4-6 hours. Intravenous: immediate (within minutes). |
| Duration of Action | Oral: 6-8 hours (immediate-release) due to rapid redistribution; extended-release: 12-24 hours. IV: 2-4 hours for anticonvulsant effect. |
40-80 mEq intravenously per day, infusion rate not exceeding 10 mEq/hour; or 20-40 mEq orally 2-4 times daily.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR >50 mL/min: no adjustment; GFR 30-50 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 starting dose by 25%; Child-Pugh C: avoid use or reduce dose by 50% with monitoring. |
| Pediatric use | 0.5-1 mEq/kg intravenously per dose, not to exceed 1 mEq/kg/hour; or 1-3 mEq/kg/day orally divided 2-3 times daily. |
| Geriatric use | Initiate at low end of dosing range (20-40 mEq/day) due to age-related decline in renal function; monitor serum potassium and renal function closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for K+8 (K+8).
| Breastfeeding | Potassium is a normal component of breast milk. Supplementation in physiological doses does not pose risk to infant. M/P ratio: ~0.4-0.5 (similar to serum). No contraindication with breastfeeding. |
| Teratogenic Risk | Potassium supplementation (K+8) is not teratogenic. Normal maternal potassium levels are essential for fetal development. Hypokalemia or hyperkalemia may pose risks. First trimester: No evidence of teratogenicity. Second/third trimester: Monitor for electrolyte imbalance; hyperkalemia can cause fetal arrhythmias. |
■ FDA Black Box Warning
Potassium chloride injection concentrate must be diluted before use; direct injection can cause fatal hyperkalemia.
| Serious Effects |
Hyperkalemia; severe renal impairment with oliguria or anuria; untreated Addison's disease; acute dehydration; extensive tissue breakdown (e.g., burns); concurrent use of potassium-sparing diuretics.
| Precautions | Monitor serum potassium levels; caution in renal impairment, cardiac disease, acidosis; risk of hyperkalemia; avoid rapid intravenous infusion; use with caution in patients receiving potassium-sparing diuretics. |
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| Fetal Monitoring |
| Serum potassium levels should be monitored regularly, especially in renal impairment, hypertension, or concurrent use of potassium-altering drugs. In pregnancy, monitor renal function and ECG if hyperkalemia suspected. Fetal monitoring for arrhythmias if maternal hyperkalemia occurs. |
| Fertility Effects | No known adverse effects on fertility. Potassium homeostasis is important for normal reproductive function; both hypokalemia and hyperkalemia may impair fertility. |