This study guide provides an overview of the basics of this medication class. It also contains practice questions for your benefit as well. So if you’re ready, let’s get started.
What are Methylxanthines?
Methylxanthines are a class of medications that are derived from a purine base known as xanthine, which is produced naturally. They work by increasing the amount of cAMP in smooth muscle tissues which ultimately results in bronchodilation.
Examples of Xanthine Drugs:
- Theophylline
- Aminophylline
- Theobromine
- Caffeine
Methylxanthines are often effective in treating infants with a poor respiratory drive and those experiencing episodes of apnea. This is especially true in premature and low-birth-weight infants.
Xanthine Drugs Practice Questions:
1. What are xanthines?
They are also called methylxanthines and are considered to be ‘side-door’ or secondary bronchodilators.
2. What are some examples of xanthines?
Theophylline, caffeine, and theobromine.
3. What are the uses of xanthines?
Asthma management, COPD management, and Apnea of prematurity.
4. What is caffeine citrate?
It is the drug of choice for apnea of prematurity.
5. What are the effects of xanthines?
CNS stimulant, smooth muscle relaxation, diuresis, and cerebral vasoconstriction.
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6. What are the serum levels of theophylline?
5 to 10 for COPD, 5 to 15 for asthma and keep under 20, in general.
7. What are the side effects of xanthines?
Nausea, vomiting, diuresis, hypotension, cardiac arrhythmias, headaches, and tremors.
8. What is the therapeutic range of theophylline?
10 to 20 mcg/ml.
9. What are the three bronchodilators used for the lower respiratory tract?
Xanthine derivatives, sympathomimetics/beta-adrenergic agonists, and anticholinergics.
10. What do xanthine drugs do?
Xanthines have a direct effect on the smooth muscles of the respiratory tract and blood vessels and it provides symptomatic relief or prevention of bronchial asthma.
11. What is the prototype for xanthines?
Theophylline (Slo-bid, Theodor) and aminophylline (
12. What are xanthines primarily used for?
It is primarily used for prevention of asthma symptoms and relief of acute asthma attacks and it is readily absorbed from GI tract and can be taken with food.
13. What are the major adverse effects of xanthines?
GI: N/V/D and anorexia (first sign of toxicity); CV stimulation:
14. What is caused by xanthines which resemble adrenergic medicines?
Neurologic stimulation.
15. What is the serum level of theophylline?
10-20 mcg/mL.
16. Why are levels drawn at first dose when taking xanthine?
Because there is no antidote so standard first aid measured must be used: charcoal, gastric lavage
17. What should be monitored when taking xanthines?
Monitor HR, RR, BP (resemble
18. How are xanthines used in asthma?
Theophylline is used as a maintenance therapy and is used for patients older than 5 years of age.
19. How are xanthines used in COPD?
Theophylline is recommended as an alternative to B2-agonists and anticholinergics. It is not to be used in acute exacerbations.
20. How are xanthines used in apnea of prematurity?
First line treatment and theophylline most extensively used in the past, but caffeine citrate may be a
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21. Where does theophylline come from?
Tea leaves.
22. Where does theobromine come from?
Cocoa seeds or beans.
23. What are the effects xanthines on humans?
CNS stimulation, cardiac muscle stimulation, diuresis, bronchial, uterine, vascular smooth muscle relaxation (theophylline is classified as a bronchodilator), peripheral, coronary vasodilation and
24. Why do we titrate theophylline doses?
Individuals metabolize theophylline at different rates and difficult to determine therapeutic doses.
25. What is the therapeutic action of xanthines?
Effect on smooth muscles of the respiratory tract.
26. What is the pharmacokinetics of xanthines?
Rapidly absorbed from the GI tract, widely distributed and metabolized in the liver, excreted in the urine.
27. What are the adverse effects of xanthines?
Theophylline levels: GI upset, irritability, tachycardia, seizures, brain damage, and death.
28. What are the contraindications for xanthines?
GI issues, coronary disease, respiratory dysfunction, renal/hepatic disease, alcoholism
29. What is theophylline?
Brand names: Theochron, Elixophyllin, Theo-24; and, formulations: tablets, capsules, syrup, elixir, extended-release tablets, capsules, and injections.
30. What is oxtriphylline?
Brand names: Choledyl SA; and, formulations: tablets, syrup, elixir, and
31. What is aminophylline?
Brand names: Aminophylline; and, formulations: tablets, oral liquid, injection, and suppositories.
32. What is dyphylline?
Brand names: Lufyllin; and, formulations: tablets and elixir.
33. What are some common side effects of xanthines?
Gastric upset, headache, anxiety, irritability, tachycardia, seizures
34. How are xanthines commonly used in apnea of prematurity?
Caffeine citrate is preferred over theophylline and loading dose of 20mg/1kg, then 5mg/kg daily.
35. What is the rapid theophyllinization dosage?
Oral loading dose of 5mg/kg of ideal body weight.
36. What is the slow theophyllinization dosage?
The initial dose of 16mg/kg/ 24 hr or 400mg/24 hour and choose whichever less is.
37. What is a methylxanthine (xanthine)?
They are inhibitor drugs that indirectly increase the amount of cAMP in smooth muscles. They are given by tablet, IV or injection.
38. What is apnea of prematurity?
When a premature baby is born they have a tendency to not breathe.
39. What are the two main drug classifications of xanthines?
Theophylline and caffeine.
40. What are some of the physiologic effects of xanthines that have generally stimulant properties?
CNS stimulation, cardiac muscle stimulation, bronchial smooth muscle relaxation, cerebral vasoconstriction, and diuresis.
41. What is the safe therapeutic blood level of theophylline?
10-20 mcg/ml to optimize bronchodilation.
42. What level should theophylline
5-10 mcg/ml.
43. When can theophylline toxicity occur?
When the serum level exceeds 20 mcg/ml.
44. What are the signs of theophylline toxicity?
Tremors, nausea, vomiting, seizures, tachycardia
45. What examples are theophylline and caffeine?
Methylxanthines
46. What condition do premature neonates have to use theophylline and caffeine for treatment?
Apnea.
47. If COPD patient is using combivent and is also taking inhaled corticosteroids, what could be recommended as long as the patient is not experiencing an acute exacerbation?
Theophylline
48. What type of drugs are xanthines?
A third class drug.
49. What is the mechanism of action of xanthines?
It is unclear, unfortunately.
50. Alkaline substances from plants which when reacted with acids form salts?
Alkaloids.
51. What are drugs derived from xanthines?
Methylxanthines
52. What enzymes changes intracellular signaling?
Phosphodiesterase.
53. What is the xanthine of choice to treat apnea of premature neonates?
Caffeine citrate.
54. If you are working in the neonatal intensive care unit and discover your patient has apnea of prematurity, you should suggest a plan for dosing what?
Caffeine citrate.
55. How does caffeine citrate work in infants?
Stimulates breathing and has a high therapeutic index with fewer side effects than theophylline.
56. Why is theophylline classified as a bronchodilator?
It has a relaxing effect on bronchial smooth muscles.
57. What are the three main physiological effects produced by xanthines?
Cardiac muscle stimulation, central nervous system stimulation, and bronchial smooth muscle relaxation.
58. What are three possible theories explaining how theophylline works?
Inhibition of phosphodiesterase, antagonism of adenosine, and catecholamine release.
59. What two things are stimulated by caffeine?
Skeletal muscles and the central nervous system.
60. Why is it difficult to determine the therapeutic doses of theophylline?
Because individuals metabolize theophylline at different rates.
61. What is 5 mg/kg known as?
Ideal body weight.
62. What is 100% theophylline known as?
Anhydrous theophylline.
63. What is the current recommended blood serum theophylline level for the management of asthma?
5-15 ug/mL
64. What is the current recommended blood serum theophylline level for the management of COPD?
5-10 ug/mL.
65. How is the dosage of theophylline best monitored?
By measuring serum drug levels.
66. What is a significant side effect of theophylline?
Nausea.
67. What includes less toxic side effects of theophylline therapy?
68. What will cause an increase in blood theophylline levels?
Renal failure.
69. What three conditions increase theophylline blood levels?
Pneumonia, corticosteroids, and Beta-blockers.
70. What are five disadvantages of theophylline therapy?
Narrow therapeutic margin, toxic effects, unpredicted blood levels, need for individual dosing, and numerous drug-drug and drug-condition interactions.
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71. What are five factors that will increase theophylline levels?
Alcohol, Beta-blocking agents, zileuton, calcium channel blockers, and influenza virus vaccine.
72. What are three factors that will decrease theophylline levels?
Isoniazid, loop diuretics, and rifampin.
73. What two things does theophylline increase within respiratory muscles?
Strength and endurance.
74. What are the three anti-inflammatory effects of theophylline?
Decreased migration of activated eosinophils into
75. What four main side effects of theophylline?
Restlessness, supraventricular tachycardia, hypotension, and nausea.
76. What four things do theophylline produces within the body?
Increased phrenic nerve activity, anti-inflammatory effect, increased ventilatory
77. Is caffeine a type of Methylxanthine Drug?
Yes, yes it is.
78. When are Methylxanthine Drugs effective in treating infants?
They are effective in treating infants with poor respiratory drive and those with low birth-weights.
79. What are the side effect of Methylxanthines?
Nausea, anxiety, tremors, arrhythmias, and seizures.
80. What are the recommended levels of serum theophylline?
8-10 mcg/mL.
71. What are five factors that will increase theophylline levels?
Alcohol, Beta-blocking agents, zileuton, calcium channel blockers, and influenza virus vaccine.
72. What are three factors that will decrease theophylline levels?
Isoniazid, loop diuretics, and rifampin.
73. What two things does theophylline increase within respiratory muscles?
Strength and endurance.
74. What are the three anti-inflammatory effects of theophylline?
Decreased migration of activated eosinophils into
75. What four main side effects of theophylline?
Restlessness, supraventricular tachycardia, hypotension, and nausea.
76. What four things do theophylline produces within the body?
Increased phrenic nerve activity, anti-inflammatory effect, increased ventilatory
77. Is caffeine a type of Methylxanthine Drug?
Yes, yes it is.
78. When are Methylxanthine Drugs effective in treating infants?
They are effective in treating infants with poor respiratory drive and those with low birth-weights.
79. What are the side effect of Methylxanthines?
Nausea, anxiety, tremors, arrhythmias, and seizures.
80. What are the recommended levels of serum theophylline?
8-10 mcg/mL.
Final Thoughts
Hopefully, this study guide can help make that process easier for you. We also have a guide on Adrenergic Bronchodilators that I think you will enjoy. Thanks for reading and as always, breathe easy my friend.
References
The following are the sources that were used while doing research for this article:
- Faarc, Gardenhire Douglas EdD Rrt-Nps. Rau’s Respiratory Care Pharmacology. 10th ed., Mosby, 2019. [Link]
- Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020. [Link]
- “Therapeutic Effects of Xanthine Oxidase Inhibitors: Renaissance Half a Century after the Discovery of Allopurinol.” PubMed Central (PMC), 1 Mar. 2006, www.ncbi.nlm.nih.gov/pmc/articles/PMC2233605.
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