Just 50 drugs account for 40 per cent of total pharmaceutical costs.
The disclosure from Daman, which insures about 2.3 million people, comes as the Government moves to slash the prices of medicines blamed for runaway healthcare spending.
Some of the costliest drugs are for treating chronic conditions such as diabetes and cardiovascular disease. They include Lipitor to treat high cholesterol, the diabetes drug Janumet and Norvasc for high blood pressure.
The Government said last week it would slash the prices of more than 6,600 medicines by up to 40 per cent in its latest attempt to curb double-digit medical inflation.
"The decision will probably affect the rate at which the premiums are increasing but a full assessment can only be made once new prices come into effect," said Dr Jad Aoun, chief medical officer at Daman.
Drugs account for up to a fifth of Daman's costs for its enhanced plans.
A senior health sector analyst said many other health insurers would find that some of Daman's costliest drugs would also be among their biggest pharmaceutical outgoings as they serve the same population.
Daman's bill might be slightly bigger, said the analyst, as the insurer tends to have a larger proportion of UAE nationals, who are at statistically higher risk of some of the diseases the medicines are used to treat, such as diabetes.
Outpatient medical inflation has been running at an average of 26 per cent a year since 2007, according to the insurer, and the Government hopes the drugs price cut will cut some of this cost.
"From what I can tell, it is mostly negotiated … with the manufacturers themselves. I would say that it is the manufacturers who will be hurt the most," said the analyst.
However, manufacturers have said the cuts are manageable.
And some, such as Julphar, a pharmaceutical company in Ras Al Khaimah, even welcomed the announcement.
"We welcome this decision by the Ministry of Health, as we all work towards greater access to better medicines across the region. Julphar congratulates this initiative and is ready to cooperate in any way," said Julphar chief executive Dr Ayman Sahli.
Samah Sabry, a pharmacist at Al Manara Pharmacy in Marina Mall, dispenses most of the drugs named on Daman's top 10 list, between three and four times a day.
She said the pharmacy dispensed more drugs to treat diabetes, cholesterol and high blood pressure - conditions covered by six of the 10 drugs on the list - than any other health complaints.
Humira, used to treat rheumatoid arthritis, was relatively rare, and while the rest were popular they were by no means the most expensive available.
"We have too many more expensive drugs than those ones," she said.
The overall challenge of reining in medical inflation will difficult because of the way bills are paid.
"What drives it is the fact that no one actually pays for their own healthcare costs because it's this third party insurer who does most of the paying," said the analyst.
"No one has an incentive to keep the prices low. Providers have an incentive to charge more and to do more and to do more procedures. If it's free to go and see a doctor you go for anything you want to. That's really the main obstacle."
More than 10 per cent of health spending in the capital goes towards treating cardiovascular disease and 8.6 per cent to diabetes.