SLO-BID
Clinical safety rating
cautionComprehensive clinical and safety monograph for SLO-BID (SLO-BID).
Relaxes smooth muscle of bronchial airways and pulmonary blood vessels by inhibiting phosphodiesterase, increasing intracellular cAMP, and promoting bronchodilation.
| Metabolism | Primarily hepatic via CYP1A2 and CYP3A4; also metabolized by CYP2E1 and xanthine oxidase. |
| Excretion | Renal: 90% as metabolites (caffeine, theobromine, paraxanthine, and unchanged drug; 1,3-dimethyluric acid, 1-methyluric acid, and 3-methylxanthine). Biliary/fecal: <10%. |
| Half-life | Terminal elimination half-life: 3-15 hours (mean ~10 hours in adults; 20-30 hours in neonates; 1-5 hours in smokers). Clinically, half-life decreases with smoking, increases with hepatic disease, heart failure, and certain drugs (e.g., cimetidine, ciprofloxacin). |
| Protein binding | ~40% bound to albumin. |
| Volume of Distribution | 0.45 L/kg (range 0.3-0.7 L/kg). Distributes into total body water; higher Vd in neonates and patients with hepatic cirrhosis. |
| Bioavailability | Oral immediate-release: 96-100%; oral sustained-release: 90-100% (relative to immediate-release, with dose dumping risk if formulation is altered). |
| Onset of Action | Oral immediate-release: 15-30 minutes; oral sustained-release: 30-60 minutes; intravenous: immediate. |
| Duration of Action | Oral sustained-release: 8-12 hours; intravenous: 4-6 hours. Clinical effect lasts until serum concentration falls below therapeutic range (5-15 mcg/mL). |
| Molecular Weight | 180.16 |
Dose: 300-600 mg orally every 12 hours. Immediate-release: 5 mg/kg loading dose then 3 mg/kg every 6 hours. Extended-release: 10-15 mg/kg/day divided every 12 hours. Titrate to serum theophylline concentration of 5-15 mcg/mL.
| Dosage form | CAPSULE, EXTENDED RELEASE |
| Renal impairment | No routine adjustment needed. Monitor for accumulation in severe impairment (CrCl <10 mL/min) and consider reducing dose or extending interval. |
| Liver impairment | Child-Pugh Class A: reduce dose by 50%; Class B or C: reduce dose by 50-75% and monitor levels. |
| Pediatric use | Children 1-9 years: 20-24 mg/kg/day orally divided every 12 hours; children 9-12 years: 20 mg/kg/day; adolescents 12-16 years: 18 mg/kg/day. Use ideal body weight. Adjust based on serum theophylline levels. |
| Geriatric use | Start at lower end of dosing range (e.g., 300 mg/day) due to decreased clearance. Titrate slowly and monitor serum concentrations. Avoid sustained-release formulations if hepatic impairment present. |
| 1st trimester | Theophylline crosses the placenta. Use only if clearly needed. Available data show no increased risk of major congenital malformations, but adverse effects such as neonatal apnea and tachycardia have been reported. |
| 2nd trimester | Continue only if maternal benefit outweighs fetal risk. Monitor maternal serum levels to avoid toxicity, as pregnancy may alter clearance. |
| 3rd trimester | Use with caution. Theophylline clearance decreases in late pregnancy; adjust dose to maintain therapeutic levels. Neonatal withdrawal (jitteriness, tachycardia) may occur. |
Clinical note
Comprehensive clinical and safety monograph for SLO-BID (SLO-BID).
| Placental transfer | Theophylline readily crosses the placenta, with cord blood levels similar to maternal serum levels. |
| Breastfeeding | Theophylline is excreted into breast milk in low amounts (approx. 10% of maternal serum level). Peak milk levels occur 1-2 hours after dosing. Although generally considered compatible with breastfeeding, observe infant for signs of irritability or poor feeding. The manufacturer advises caution. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | SLO-BID (theophylline) is classified as FDA Pregnancy Category C. First trimester: Limited human data, but no clear teratogenic pattern observed. Second and third trimesters: Theophylline crosses the placenta; maternal toxicity may cause fetal adverse effects such as transient tachycardia, jitteriness, and vomiting in neonates. Apnea and seizures reported in cases of maternal overdose. |
| Fetal Monitoring | Monitor maternal serum theophylline concentrations (target 5–15 mcg/mL), heart rate, respiratory rate, and signs of toxicity. Fetal monitoring includes heart rate assessment via nonstress test or biophysical profile if indicated for asthma exacerbation. Neonatal monitoring for transient tachycardia, irritability, and feeding difficulties after delivery. |
| Fertility Effects | No known significant effects on fertility in humans based on available data. In animal studies, no adverse reproductive effects at clinically relevant doses. |
■ FDA Black Box Warning
Theophylline has a narrow therapeutic index. Severe and fatal toxicities can occur if serum concentrations exceed 20 mcg/mL. Serum levels must be closely monitored during therapy.
| Serious Effects |
Hypersensitivity to theophylline or any component of the formulationUncontrolled seizure disorderSevere cardiac arrhythmias (e.g., ventricular tachycardia)
| Precautions | Serious and life-threatening adverse reactions including seizures and cardiac arrhythmias can occur at serum levels above 20 mcg/mL., Concomitant use with other xanthine derivatives may increase toxicity., Use with caution in patients with peptic ulcer, seizures, cardiac disease, or hepatic impairment. |
| Food/Dietary | High-fat meals may reduce the rate of absorption but not extent; take consistently with or without food. Avoid charcoal-broiled foods and large amounts of dietary protein, which can increase clearance. Grapefruit juice may increase theophylline levels (minor effect). |
| Clinical Pearls | SLO-BID (theophylline) requires serum level monitoring (therapeutic range 10-20 mcg/mL); levels >20 may cause toxicity. Use with caution in heart failure, hepatic impairment, or elderly due to reduced clearance. Drug interactions: cimetidine, fluoroquinolones, macrolides increase levels; rifampin, phenytoin, smoking decrease levels. Sustained-release formulation avoids peak-trough fluctuations and improves adherence. |
| Patient Advice | Take exactly as prescribed; do not crush or chew the sustained-release tablet. · Avoid excessive caffeine intake (coffee, tea, cola) as it may increase side effects. · Report symptoms of toxicity: nausea, vomiting, restlessness, insomnia, or rapid heartbeat. · Do not stop abruptly; taper under medical supervision to prevent rebound symptoms. · Maintain consistent timing; missed doses should be taken if remembered within 2 hours, otherwise skip. |
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