How much dytan CS can I give my 9 year old daughter 91 lbs bad cough and congestion

my dauthter is 9 years old weighs 91 pounds. She has been coughing and full of mucous in her lungs. I took her to her pediatrician 3 days ago. She is now taking antibiotic azithromycin 250 mg tablets 1 per day for 5 days. My daughter will not take a liquid cough medicine or any liquid medicine for that matter. They make her gag. Is this medicine safe for my daughter to take 2 times a day at such a young age because it is for adults right? I have been breaking the pill in half.