Pharmacology of Xanthines in Respiratory Treatment

Xanthines

• Administered as sustained-release formulations alongside adrenergics and anticholinergics to enhance symptom relief and improve breathing.
• Theophylline side effects range from mild to severe, including:
  • GI distress: nausea, vomiting, abdominal pain, anorexia, diarrhea; best taken with meals to minimize irritation.
  • CNS stimulation: nervousness, insomnia, headaches, tremors, seizures which can be fatal.
  • Cardiac issues: palpitations, tachycardia, arrhythmias, particularly with rapid IV administration.
  • Increased urinary frequency and mild diuresis.
  • Hyperglycemia.

Cautions and Contraindications for Theophylline

• Increased serum levels due to sudden cessation of tobacco smoking.
• Not recommended for patients with cardiovascular, kidney, pulmonary, or liver dysfunction.
• Use with caution in diabetes, peptic ulcer, glaucoma, children, and older adults.
• Slow IV injection is necessary to avoid cardiac side effects.
• Careful in patients receiving influenza immunizations or during pregnancy and lactation.

Drug Interactions with Theophylline

• Increased levels due to cimetidine, allopurinol, certain antibiotics, oral contraceptives, and others.
• Reduced effectiveness with smoking, barbiturates, phenytoin, rifampin, PDE-4 inhibitors.

Bronchodilator Corticosteroids

• Used to reduce inflammation, bronchial hyper-responsiveness, and control acute symptoms.
• Inhaled corticosteroids are preferred for long-term asthma management and are not for acute treatment.
• Regular use improves asthma control and reduces hospitalization and mortality.

Antitussives

• Side effects include respiratory depression, constipation, urinary retention, sedation, dizziness, and nausea.
• Caution advised for addiction-prone individuals and patients with asthma or COPD.

Antihistamines

• Block histamine action to reduce symptoms from allergies (e.g., rhinitis, conjunctivitis).
• First-generation antihistamines (e.g., diphenhydramine) may cause more side effects (sedation, dry mouth, urinary retention).
• Second-generation antihistamines (e.g., loratadine) are less sedating and suited for treating seasonal allergic rhinitis.

Cautions for Antihistamines

• Contraindicated in COPD, asthma, closed-angle glaucoma, cardiovascular disorders, and older adults due to sedation risks.

Decongestants

• Used to relieve nasal congestion with side effects including palpitations, anxiety, and nausea.
• Caution in patients with cardiovascular issues, hyperthyroidism, diabetes, and pregnant or lactating women.

Cough–Cold-Allergy Products

• Combination formulations must match symptoms, and caution is necessary to avoid overdosing from overlapping ingredients.
• In 2011, the FDA removed many unapproved cough and cold products, particularly those for children due to safety concerns.

Smoking Cessation Aids

• Cigarette smoking is a leading cause of preventable disease and death.
• Nicotine Replacement Therapies (e.g., gum, patches) double effectiveness compared to cold turkey methods.
• E-cigarettes provide a less toxic alternative to traditional smoking but lack long-term safety data.

This quiz covers the use of xanthines in respiratory therapy, focusing on their administration, potential side effects, and the interactions with other respiratory medications. Test your knowledge on the toxicity and management of xanthine-based treatments for respiratory conditions.