Albuterol

Limits on what this shows

• Null and small-effect findings: Newhouse 1996 [32]: multicenter randomized double-blind trial in emergency-department adults with acute severe asthma (FEV1 under 50% predicted), 129 given albuterol by metered-dose inhaler and holding chamber, 4 puffs then 2 puffs every 10 minutes up to 16 puffs (1600 micrograms over 90 minutes). Serum potassium fell only 0.06 +/- 0.03 mmol/L (fenoterol at twice the dose, 0.23 +/- 0.04, p = 0.0002 between drugs); QTc rose 0.003 +/- 0.003 s; no sustained ventricular tachycardia and no clinically significant arrhythmia in either group. Magnitude at ordinary rescue doses is otherwise modest: 0.3 mmol/L in adults at 2.5 mg nebulized three times [11], 0.2 mEq/L mean in children [12]. Long-term tolerance of the potassium effect (fading with regular use) was not tested in any source retrieved; the thermogenic response did fade with regular inhalation [36], which is a different beta-2 response.
• At-risk subgroups: People given repeated or continuous high-dose nebulization, those on loop or thiazide diuretics (label), children with recent oral salbutamol [12], and people with existing cardiac disease (label cardiovascular warning).

Direction

Redistribution (disturbance of the blood level). Not depletion, not renal wasting, not a dietary shortfall.

Regulatory status

Named in all three labels read. HFA label sec 5.8: "As with other beta-agonists, Albuterol Sulfate HFA Inhalation Aerosol may produce significant hypokalemia in some patients"; the decrease is usually temporary and typically needs no supplementation; it may cause adverse cardiovascular effects. Tablet and inhalation-solution labels: "possibly through intracellular shunting". Non-potassium-sparing diuretics worsen the effect [1][2][3].

Population evidence

Five independent cohorts, potassium measured directly, albuterol or salbutamol the studied drug. (1) Scheinin 1987 [9]: 6 healthy men, inhaled salbutamol 1200, 1800 and 2400 micrograms cumulative over 1 hour; dose-dependent fall peaking at 75 to 90 minutes, 0.67 +/- 0.25 mEq/L at the highest dose (fenoterol 1.13 +/- 0.32), T-wave amplitude fell, plasma cAMP mirrored potassium. (2) Zitek 2016 [7]: randomized double-blind placebo-controlled trial, 28 healthy adults (14 per arm), 10 mg nebulized over 1 hour; potassium fell 0.5 mEq/L (95% CI -0.72 to -0.28) versus 0.0 (95% CI -0.21 to 0.21) with saline, p = 0.003. (3) Lipworth 1989 [10]: 14 asthmatics, cumulative inhaled doses from 100 to 4000 micrograms; potassium change at 4000 micrograms -0.38 mmol/L (95% CI -0.64 to -0.12), linear in log dose. (4) Allon 1989 [8]: 10 hemodialysis patients with chronic hyperkalemia, double-blind placebo-controlled, nebulized 10 mg and 20 mg; maximal falls 0.62 +/- 0.09 and 0.98 +/- 0.14 mmol/L (SE), saline no change, effect present by 30 minutes and sustained for at least 2 hours. (5) Sahan 2013 [11]: 26 adults with acute asthma, 2.5 mg nebulized three times hourly; potassium 4.6 +/- 0.7 to 4.3 +/- 0.7 mmol/L at 60 minutes, p < 0.001. Pediatric: Singhi 1996 [12], 46 children, three nebulized doses of 0.15 to 0.3 mg/kg every 30 minutes; mean potassium 3.9 +/- 0.5 to 3.7 +/- 0.5 mEq/L (p < 0.05), potassium below 3.5 in 17 children (39%), more often after oral salbutamol in the prior 7 days. Hartman 2015 [13]: retrospective, 279 children admitted with asthma; effect sizes were not retrievable (see Sources).

Mechanism

Named. Beta-2 stimulation raises cAMP and drives sodium-potassium ATPase-mediated uptake of potassium into skeletal muscle. Plasma cAMP rose as a mirror image of the potassium fall in healthy volunteers [9]; the label itself attributes the fall to intracellular shunting [2][3]. With intravenous salbutamol the fall reversed within 30 minutes of stopping the infusion [14].

Redistribution versus true depletion

No source retrieved shows a loss of total body potassium from albuterol. Measured falls are transient and track dose and time after dosing. Muscle potassium content did not differ from healthy controls in 20 asthmatics on long-term oral beta-2 agonists (the abstract does not name the agents, so this is CLASS EXTRAPOLATION and the drug's presence in that cohort is unconfirmed) [16]. The same study found serum potassium lower in asthmatics than in controls both on treatment (4.0 +/- 0.2) and 2 months after withdrawal (3.9 +/- 0.2) versus 4.2 +/- 0.2, so part of any chronic shortfall belongs to asthma, not the drug [16].

Near-red note

Count criteria for red are met (five independent Tier A cohorts, direct measurement, consistent direction, named mechanism). Held at orange because the clinically meaningful size is dose- and route-bounded and the largest albuterol trial [32] showed a very small fall at metered-dose inhaler doses. An editor who weighs the count above the dose boundary could promote it.

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Albuterol can lower blood potassium for a few hours, mainly with high-dose nebulized or repeated use; the shift reverses by itself and is not a potassium deficiency.

Counter-evidence held on record

Counter-evidence and confounding The direction is not contradicted by any Tier A source, but size depends on dose and delivery. Confounders in the observational pediatric data include severity of attack, concurrent corticosteroids and theophylline, and prior oral salbutamol, so they support the frequency of low values, not the size attributable to the drug. The healthy-volunteer and placebo-controlled studies [7][9] remove the disease confounder. Hartman 2015 [13] is a letter whose results were not retrieved, so it is not counted toward the grade. Framing caution This is a short-lived shift of potassium into cells after dosing, not a dietary potassium deficiency. The label says it is usually temporary and typically does not require supplementation. Adding potassium to correct a shift that reverses by itself is not supported and could overshoot as the shift unwinds (mechanistic reasoning, not a studied outcome). This entry is an excess-and-disturbance risk, never a prompt to supplement.

Limits on what this shows

• Null findings: In asthma, hyperlactatemia was not associated with hospitalization or 1-week relapse (p =.26) or with lower FEV1 at 3 hours (p =.54) [17]. The metabolomic authors state the changes may not be clinically significant [18]. Bicarbonate did not change significantly (22.6 to 21.9 mEq/L, p =.11) [17].
• At-risk subgroups: People on continuous or repeated high-dose nebulization and those with intravenous exposure. Case reports of lactic acidosis exist (the 68-record PubMed listing for albuterol lactic acidosis is mostly case reports; individual cases were not read).

Direction

Excess (rise in a metabolite). Not a nutrient deficiency, and not evidence of mitochondrial damage.

Regulatory status

HFA label postmarketing reactions list hyperglycemia and metabolic acidosis; the highlights state that hypokalemia and changes in blood glucose may occur [1]. Lactate by name was not found in the label text retrieved.

Population evidence

Zitek 2016 [7]: randomized placebo-controlled, 28 healthy adults, 10 mg nebulized over 1 hour; lactate +0.77 mmol/L (95% CI 0.52 to 1.02) versus -0.15 (95% CI -0.39 to 0.09) with placebo, p < 0.0001. Nowadly 2021 [18]: 24 healthy volunteers, 7.5 mg continuous over 1 hour, uncontrolled before-after; lactate 1.45 +/- 0.46 mmol/L at baseline, +0.33 +/- 0.67 at 1 hour (p =.02), still +0.32 at 2 hours. Lewis 2014 [17]: secondary analysis of the placebo arm of a trial, 84 placebo patients with 65 analyzable, mean albuterol 12.3 mg before baseline; lactate rose from 18.5 to 26.5 mg/dL at 1.25 hours (p <.001), 45 patients (69.2%) developed hyperlactatemia, and plasma albuterol correlated with lactate (beta 0.45; 0.41 after adjusting for asthma severity). Phillips 1980 [15]: intravenous salbutamol in 4 healthy men, significant hyperlactataemia and ketonaemia. Smith 2019 [19]: systematic review of 101 reports (286 patients, 59 drugs) naming epinephrine and albuterol as the most commonly implicated agents; no albuterol-specific counts were retrievable.

Mechanism

Named. Beta-2 stimulation of glycolysis, glycogenolysis and free fatty acid release. The metabolomic study found fatty acids, organic acids and sugars up and amino acids down, with lactate and pyruvate-related metabolites not significant after multiple-testing adjustment [18].

Near-red note

Three independent Tier A cohorts agree on direction (Zitek [7], Nowadly [18], Lewis [17]) with a named mechanism and a systematic review naming albuterol among the most commonly implicated drugs [19]. Held at orange because the mean rise is small and no clinical outcome link was found [17][18]. Missing for red: albuterol-specific counts from the systematic review and a clinical-outcome analysis.

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Transient lactate rise after acute, high-dose albuterol; usually small; not shown to harm outcomes in asthma.

Counter-evidence held on record

Counter-evidence and confounding Acute asthma itself raises lactate through work of breathing and hypoxia, so observational asthma data [17] cannot isolate the drug; the placebo-controlled healthy-volunteer trial [7] does. The mean rise in volunteers was under 1 mmol/L [7][18]. This entry stays orange, not red, because the magnitude is modest and the one outcome analysis found no clinical association. Framing caution A metabolic effect of the drug in the excess direction, not a nutrient shortfall. Do not recommend thiamine or any supplement from this entry. Unexplained rising lactate in a high-dose albuterol patient is a clinical question for a clinician.

Limits on what this shows

• Null findings: No insulin change with intravenous salbutamol in normal subjects [14]. No glucose result was available for the 2.5 mg nebulizer cohort [11]. Clinical consequence at routine inhaled doses was not quantified in any source retrieved.
• At-risk subgroups: People with diabetes or impaired glucose tolerance, particularly with intravenous or repeated high-dose dosing (label) [1][3][15].

Direction

Excess (rise in a circulating metabolite). Not a nutrient deficiency.

Regulatory status

HFA label: "Large doses of intravenous albuterol have been reported to aggravate preexisting diabetes mellitus and ketoacidosis"; postmarketing hyperglycemia and metabolic acidosis; highlights: changes in blood glucose may occur [1]. The nebulizer-solution label repeats the intravenous statement and does not describe glucose effects at inhaled doses [3]. The tablet label read does not mention glucose [2].

Population evidence

Lipworth 1989 [10]: 14 asthmatics, cumulative inhaled salbutamol 100 to 4000 micrograms in doubling doses every 20 minutes; at 4000 micrograms glucose rose 1.46 mmol/L (95% CI 0.83 to 2.09), linear in log dose, with wide individual variation; the authors note this dose range is similar to current nebulizer therapy (2.5 to 5 mg). Phillips 1980 [15]: intravenous salbutamol in 4 healthy men gave dose-related rises in plasma glucose and insulin. Whyte 1987 [14]: during an intravenous salbutamol infusion in 8 normal subjects insulin did not change significantly (glucose change with salbutamol is not stated in the abstract summary; the glucose rise was reported with adrenaline). A study of oral albuterol on lipids and carbohydrate metabolism in healthy men exists (Maki 1996 [33]) but only its title and metadata were retrieved.

Mechanism

Named. Beta-2 stimulated hepatic glycogenolysis and gluconeogenesis, with free fatty acid mobilization [10][15][18].

Near-red note

One inhaled Tier A study with a CI [10], one intravenous study [15] and the label [1][3]. Missing for red: a second inhaled study with a glucose effect size (the oral albuterol study [33] could not be read) and a placebo-adjusted estimate.

Boundary string (customer-visible)

Blood glucose rises after acute high-dose albuterol and is most relevant for people with diabetes; the effect is transient.

Counter-evidence held on record

Counter-evidence and confounding Asthma exacerbation, systemic corticosteroids and stress hormones also raise glucose, so observational data would be confounded. Lipworth [10] was a within-patient dose-escalation without a placebo arm, so it shows dose-response but not placebo-adjusted size. Only one retrieved inhaled study measured glucose. Framing caution Glucose is not a nutrient that can be low from this drug; the finding is a transient rise. Do not frame it as a deficiency or recommend a dietary or supplement change. People with diabetes should discuss glucose monitoring with their prescriber if using large or repeated doses.

Limits on what this shows

• Null findings: Lipworth 1989 [10]: inhaled salbutamol up to 4000 micrograms cumulative in 14 asthmatics, no significant change in magnesium. Gustafson 1996 [16]: serum magnesium did not differ between asthmatics on long-term oral beta-2 agonists and controls, although skeletal muscle magnesium was lower in the asthmatics both on treatment (3.62 mmol/100 g) and 2 months after withdrawal (3.43) than in controls (4.43), so the muscle deficit did not recover off the drug (agents not named in the abstract; CLASS EXTRAPOLATION, drug's presence in cohort unconfirmed).
• At-risk subgroups: Intravenous infusion, a route not covered by the three labels read. No at-risk group identified for inhaled or oral use.

Direction

Redistribution (cellular uptake lowers the blood level). Not depletion and not renal wasting.

Regulatory status

Magnesium is not mentioned in the three labels read [1][2][3].

Population evidence

Whyte 1987 [14]: placebo-controlled, 8 normal subjects; plasma magnesium fell significantly during intravenous salbutamol (more slowly than with adrenaline) and had not recovered 1 hour after the infusion stopped; insulin did not change, so the shift is not insulin-mediated. Phillips 1980 [15]: 4 healthy men, intravenous salbutamol, significant decreases in magnesium and calcium alongside falls in potassium and phosphate. The abstracts did not give magnesium effect sizes and the full texts were not read.

Mechanism

Named in the source: beta-adrenergic stimulation moves magnesium into cells independent of insulin [14]. Magnesium is not known to be lost in urine from this drug.

Near-red note

Two Tier A intravenous studies agree in direction [14][15]. Missing for red: effect sizes (the abstracts gave none), full texts, and any positive inhaled or oral study; the one inhaled study was null [10].

Boundary string (customer-visible)

Plasma magnesium falls during intravenous salbutamol; no change was seen with high-dose inhaled salbutamol.

Counter-evidence held on record

Counter-evidence and confounding Both positive sources used the intravenous route in 4 and 8 volunteers, and the one inhaled study found nothing, so extension to inhaled or oral albuterol is not supported. Low muscle magnesium in asthma is present off the drug, which points to the disease or diet, not albuterol [16]. This stays orange, not red, because the positive evidence is route-limited and no effect size was retrieved. Framing caution A short-lived shift of magnesium into cells during intravenous dosing, not a dietary shortfall. Do not recommend magnesium supplementation from this entry.

Limits on what this shows

• Null findings: Sahan 2013 [11]: 26 adults with acute asthma, 2.5 mg nebulized three times hourly; phosphate 3.7 +/- 0.9 to 3.6 +/- 0.9 mg/dL at 60 minutes, p = 0.373, while potassium fell significantly in the same patients. Lipworth 1989 [10]: phosphate was not reported in the abstract.
• At-risk subgroups: Intravenous exposure only, as in the magnesium entry.

Direction

Redistribution (cellular uptake lowers the blood level). Not depletion.

Regulatory status

Phosphate is not mentioned in the three labels read [1][2][3].

Population evidence

Phillips 1980 [15]: 4 healthy men, intravenous salbutamol; dose-related falls in plasma phosphate (and potassium), with significant decreases in calcium and magnesium. Effect sizes were not retrievable from the abstract-level record.

Mechanism

Plausible and consistent with the other beta-2 cellular shifts; not separately demonstrated for phosphate in the retrieved sources.

Near-red note

Single Tier A source [15] with four subjects. Missing for red: a second positive study, any effect size, and an inhaled study with a significant change (the one inhaled cohort was null [11]).

Boundary string (customer-visible)

Plasma phosphate fell during intravenous salbutamol in a four-person study; no significant change was seen with nebulized albuterol in asthma.

Counter-evidence held on record

Counter-evidence and confounding A single Tier A source with four subjects, no retrievable effect size, and a null result in the only inhaled cohort. This is graded orange because the rubric accepts one Tier A source with a bounded real change; it is the weakest orange entry and should be the first reviewed. The same four-person cohort supports the magnesium entry (see Overlap map). Framing caution A transient shift of phosphate into cells during intravenous dosing, not a dietary shortfall. Do not recommend phosphate supplementation from this entry.