Alkali Therapy (Metabolic Acidosis / CKD-Related Acidosis) Pregnancy: Compatible — oral sodium bicarbonate used in pregnancy for heartburn (short-term use). Caution with prolonged use or high doses — sodium load and potential alkalosis. IV use in emergency under specialist guidance.

Sodium Bicarbonate

Brand names: Various — tablets 500 mg, oral solution, IV infusion 1.26% / 4.2% / 8.4%

Adult dose

Dose: Oral CKD metabolic acidosis: 500 mg–2 g two to three times daily (target serum bicarbonate 22–24 mmol/L). IV: 50–100 mmol over 30–60 minutes for urgent correction

Route: Oral (tablets/solution) or Intravenous

Frequency: Two to three times daily (oral); bolus or infusion (IV)

Max: Oral: individualised to response (typically 3–6 g/day). IV 8.4%: maximum 100 mmol bolus for life-threatening acidosis (pH <7.1)

Oral: used in CKD metabolic acidosis (bicarbonate <22 mmol/L) to slow CKD progression. IV 8.4% (hyperosmolar): 50 mL of 8.4% = 50 mmol NaHCO3 — use for cardiac arrest with severe acidosis, hyperkalaemia with ECG changes, or tricyclic antidepressant overdose (alkalinisation). IV 1.26%: isotonic — used for prolonged infusion without volume loading. Source: BNF 90; NICE NG203.

Paediatric dose

Dose: 1–2 mmol/kg/day oral divided doses for renal tubular acidosis. IV: 1 mmol/kg over 10–15 min (cardiac arrest with severe acidosis) mmol/kg

Route: Oral or IV

Frequency: Two to three times daily (oral); once (IV bolus)

Max: See indication

Renal tubular acidosis (RTA) in children: regular oral bicarbonate is standard. IV only for acute life-threatening acidosis under specialist supervision. Source: BNF for Children 2024.

Dose adjustments

Renal

Dose titrated by serum bicarbonate level, not eGFR. Higher doses often needed as CKD progresses (reduced ammonium production). Watch for sodium load — may worsen hypertension and fluid overload in advanced CKD.

Hepatic

No dose adjustment required.

Paediatric weight-based calculator

Patient weight (kg)

Renal tubular acidosis (RTA) in children: regular oral bicarbonate is standard. IV only for acute life-threatening acidosis under specialist supervision. Source: BNF for Children 2024.

Clinical pearls

CKD acidosis slows progression — treating it helps: BASE trial (NEJM 2023): sodium bicarbonate significantly slowed eGFR decline vs placebo in non-dialysis CKD with metabolic acidosis (bicarbonate 18–24 mmol/L). BICARBONATE trial (Lancet 2020): 2-year slowing of eGFR decline. NICE NG203 now recommends correcting serum bicarbonate to ≥22 mmol/L in CKD. This is a simple, cheap, and effective intervention.
Mechanism in CKD: metabolic acidosis in CKD activates complement and promotes tubulointerstitial inflammation → accelerates nephron loss. Correction of acidosis reduces protein catabolism (muscle wasting) and bone resorption (acidosis buffers H+ with carbonate from bone). Oral bicarbonate is beneficial beyond its direct pH effect.
IV 8.4% in cardiac arrest: ALS guidelines recommend sodium bicarbonate 50 mmol IV only for peri-arrest with severe metabolic acidosis (pH <7.1) or hyperkalaemia with ECG changes, or tricyclic antidepressant toxicity (raises pH to bind sodium channels). Routine use in cardiac arrest is NOT recommended — hypernatraemia and paradoxical intracellular acidosis from CO2 generation worsen outcomes.
Sodium load monitoring in CKD: 1 g NaHCO3 = 12 mmol Na+. In CKD patients already salt-sensitive with hypertension, the sodium load of treatment doses (3–6 g/day = 36–72 mmol Na+/day) may worsen blood pressure and oedema. Monitor BP and fluid status. Some nephrologists use sodium citrate (Shohl's solution) to reduce GI side effects.
Dietary alkali: encourage vegetable-heavy, fruit-rich diet — produces metabolic alkaline residue (plant-based metabolism produces bicarbonate; meat/fish produce acid). Dietary modification can reduce bicarbonate tablet requirements. Source: BNF 90; de Brito-Ashurst et al. JASN 2009; NICE NG203; Cooper et al. Lancet 2020 (BICARBONATE).

Contraindications

Metabolic alkalosis or respiratory alkalosis (will worsen)
Hypocalcaemia (alkalosis shifts ionised calcium to bound form — may precipitate tetany)
Volume overload / pulmonary oedema (sodium load of NaHCO3 worsens fluid retention)
Hypokalaemia (alkalosis drives potassium intracellularly — exacerbates hypokalaemia)
IV use in presence of calcium-containing infusions (precipitates calcium carbonate — incompatible)

Side effects

Hypernatraemia and fluid retention (sodium content — 1 g NaHCO3 = 12 mmol Na+)
Metabolic alkalosis (over-correction — rebound alkalosis)
Hypokalemia (alkalosis shifts K+ intracellularly — supplement potassium if needed)
Hypocalcaemia (ionised calcium falls with alkalinisation — tetany risk)
Flatulence, belching, abdominal bloating (oral tablets — CO2 released in stomach)
Extravasation burns (IV 8.4% is highly alkaline — use central line for concentrated solutions)

Interactions

Tetracyclines: alkaline urine increases renal tubular reabsorption — reduces efficacy
Quinolones (ciprofloxacin): altered urinary excretion
Aspirin/salicylates: alkaline urine increases salicylate excretion — may reduce salicylate levels
Methenamine: alkaline urine prevents conversion to formaldehyde — reduces efficacy
Lithium: alkaline urine slightly reduces lithium reabsorption — monitor levels
Calcium-containing solutions (IV): precipitate — do not mix in same line

Monitoring

Serum bicarbonate (target 22–24 mmol/L — check 4 weeks after dose change, then 3-monthly)
Serum potassium (alkalosis shifts K+ intracellularly — hypokalaemia risk)
Serum calcium (ionised Ca falls with alkalinisation)
Blood pressure and fluid balance (sodium load monitoring)
Serum sodium (hypernatraemia risk especially IV use)
Arterial/venous blood gas for acute IV use

Reference: BNFc; BNF 90; BNF for Children 2024; NICE NG203 (CKD); Cooper et al. Lancet 2020 (BICARBONATE trial); de Brito-Ashurst et al. JASN 2009; ALS Guidelines 2021. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways