OXYGEN, USP
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OXYGEN, USP (OXYGEN, USP).
Oxygen serves as the final electron acceptor in the electron transport chain, enabling aerobic metabolism and ATP production. It increases arterial oxygen tension and saturation, improving tissue oxygenation.
| Metabolism | Oxygen is not metabolized; it is consumed in cellular respiration and converted to water and carbon dioxide. |
| Excretion | Oxygen is primarily eliminated via pulmonary excretion as unchanged gas. There is no significant renal, biliary, or fecal elimination. The rate of elimination depends on ventilation and cardiac output. In normal lungs, almost all administered oxygen is excreted unchanged, with negligible metabolic conversion to carbon dioxide or water. |
| Half-life | Oxygen does not have a classical terminal elimination half-life as it is a gas that equilibrates rapidly. The elimination from the body is governed by ventilation and perfusion, with a context-sensitive half-life of approximately 30-60 minutes in the blood after discontinuing supplemental oxygen, depending on the prior concentration and physiological state. |
| Protein binding | Oxygen is not significantly bound to plasma proteins. It is transported primarily bound to hemoglobin (approximately 98% in red blood cells) and dissolved in plasma (2%). No appreciable binding to albumin or other plasma proteins occurs. |
| Volume of Distribution | The apparent volume of distribution for oxygen is not typically reported as a standard pharmacokinetic parameter because it is a gas with complex distribution. However, the total body oxygen content is distributed in blood (bound to hemoglobin and dissolved) and tissues. An estimate is approximately 0.2-0.5 L/kg, reflecting rapid distribution into the central compartment and limited tissue storage. |
| Bioavailability | Inhalation: Bioavailability is nearly 100% for pulmonary absorption, as oxygen readily crosses the alveolar-capillary membrane. Intravenous (as hyperbaric oxygen): 100% bioavailability. Oral, intramuscular, subcutaneous, and other routes are not applicable or have negligible absorption. |
| Onset of Action | Inhalation: Immediate (within seconds) via the respiratory system. Intravenous (as hyperbaric oxygen): Rapid onset within minutes. The time to clinical effect (e.g., increased arterial oxygen saturation) is virtually instantaneous upon inhalation. |
| Duration of Action | The duration of action is limited to the period of administration. Once oxygen therapy is discontinued, arterial oxygen tension returns to baseline within minutes. Prolonged effects (e.g., reversal of hypoxia) last only as long as the gas is being inhaled. For hyperbaric oxygen, effect duration extends during the session and declines rapidly after decompression. |
Inhalation: 1-6 L/min via nasal cannula to achieve SpO2 ≥90%; 10-15 L/min via non-rebreather mask for severe hypoxemia; higher flow rates via Venturi mask or high-flow nasal cannula as needed.
| Dosage form | GAS |
| Renal impairment | No dose adjustment required. Monitor arterial blood gases in patients with renal failure due to risk of CO2 retention. |
| Liver impairment | No dose adjustment required. Monitor for hypoxemia in hepatic encephalopathy as oxygen demand may be altered. |
| Pediatric use | Neonates: 0.5-1 L/min via hood or nasal cannula to maintain SpO2 90-95%; Infants/Children: 1-2 L/min low flow; up to 10-12 L/min via non-rebreather for severe cases; titrate to SpO2 ≥90%. |
| Geriatric use | Start at lower flow rates (1-2 L/min) due to increased risk of oxygen-induced hypercapnia; titrate to SpO2 90-92%; monitor for respiratory depression. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for OXYGEN, USP (OXYGEN, USP).
| Breastfeeding | Oxygen is considered compatible with breastfeeding. M/P ratio is not applicable as oxygen is not a drug that concentrates in milk. It is a normal constituent of blood and milk. |
| Teratogenic Risk | Oxygen is not teratogenic. Hypoxemia poses significant fetal risk; maternal oxygen supplementation is used to treat fetal hypoxia. No known teratogenicity at therapeutic doses. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["None absolute; use with caution in patients with paraquat poisoning (increased toxicity)","Relative: patients with severe COPD and CO2 retention (risk of respiratory depression)","Relative: premature infants (risk of retinopathy of prematurity)"]
| Precautions | ["Risk of oxygen toxicity with prolonged high concentrations (e.g., pulmonary oxygen toxicity, retrolental fibroplasia in neonates)","Fire hazard: oxygen supports combustion","Hypercapnic respiratory failure: may suppress hypoxic drive in patients with COPD","Absorption atelectasis with high FiO2"] |
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| Monitor maternal arterial oxygen saturation (SpO2) and arterial blood gases. Fetal heart rate monitoring may be indicated to assess fetal oxygenation. Adjust FiO2 to maintain maternal PaO2 > 60-80 mmHg. |
| Fertility Effects | No known adverse effects on fertility. Oxygen supplementation may improve fertility outcomes in conditions associated with hypoxemia. |