Its use must be monitored by direct measurement of serum theophylline levels to avoid toxicity. It can also cause nausea, diarrhea, increase in heart rate, abnormal heart rhythms, and CNS excitation (headaches, insomnia, irritability, dizziness and lightheadedness). Seizures can also occur in severe cases of toxicity, and are considered to be a neurological emergency. Its toxicity is increased by erythromycin, cimetidine, and fluoroquinolones, such as ciprofloxacin. Some lipid-based formulations of theophylline can result in toxic theophylline levels when taken with fatty meals, an effect called dose dumping, but this does not occur with most formulations of theophylline. Theophylline toxicity can be treated with beta blockers. In addition to seizures, tachyarrhythmias are a major concern. Theophylline should not be used in combination with the SSRI fluvoxamine. Spectroscopy
UV-visible spectroscopy
Theophylline is soluble in 0.1N NaOH and absorbs maximally at 277 nm with an extinction coefficient of 10,200 (cm−1 M−1). Proton nuclear magnetic resonance spectroscopy (1H-NMR)
The characteristic signals, distinguishing theophylline from related methylxanthines, are approximately 3.23δ and 3.41δ, corresponding to the unique methylation possessed by theophylline. The remaining proton signal, at 8.01δ, corresponds to the proton on the imidazole ring, not transferred between the nitrogen. The transferred proton between the nitrogen is a variable proton and only exhibits a signal under certain conditions. Carbon nuclear magnetic resonance spectroscopy (13C-NMR)
The unique methylation of theophylline corresponds to the following signals: 27.7δ and 29.9δ. The remaining signals correspond to carbons characteristic of the xanthine backbone. Natural occurrences
Theophylline is naturally found in cocoa beans.
An old cesarean scar may undergo dehiscence; with further labor the woman may experience abdominal pain and vaginal bleeding, though these signs are difficult to distinguish from normal labor. Often a deterioration of the fetal heart rate is a leading sign, but the cardinal sign of uterine rupture is loss of fetal station on manual vaginal exam. Intra-abdominal bleeding can lead to hypovolemic shock and death. Although the associated maternal mortality is now less than one percent, the fetal mortality rate is between two and six percent when rupture occurs in the hospital. In pregnancy uterine rupture may cause a viable abdominal pregnancy. This is what accounts for most abdominal pregnancy births. Abdominal pain and tenderness. The pain may not be severe; it may occur suddenly at the peak of a contraction. The woman may describe a feeling that something "gave way" or "ripped." Chest pain, pain between the scapulae, or pain on inspiration—Pain occurs because of the irritation of blood below the womans diaphragm
Hypovolemic shock caused by bleeding, evidenced by falling blood pressure, tachycardia, tachypnea, pallor, cool and clammy skin, and anxiety. The fall in blood pressure is often a late sign of haemorrhage
Signs associated with fetal oxygenation, such as late deceleration, reduced variability, tachycardia, and bradycardia
Absent fetal heart sounds with a large disruption of the placenta; absent fetal heart activity by ultrasound examination
Cessation of uterine contractions
Palpation of the fetus outside the uterus (usually occurs only with a large, complete rupture). The fetus is likely to be dead at this point.