You should not substitute orciprenaline with the theophylline and etophylline combination without consulting your doctor. Although both act as bronchodilators to relax your airways and ease breathing, they belong to different drug classes and work differently in the body. Therefore, they are not direct substitutes. Common side effects of the theophylline and etophylline combination include a rapid or irregular heartbeat, nausea, headaches, restlessness, insomnia, and mild stomach upset. Please consult your prescribing doctor before making any changes to your medication to ensure your treatment remains safe and effective for your specific condition.