Yes, the dosage of Symbicort will definitely be greater than the dosage for Breo. However, dosages aren't equivalent from drug to drug, so I'm not entirely sure what your pulmonologist might have been referring to.
Both Breo and Symbicort are combination inhalers. They each contain an inhaled corticosteroid (or ICS, an anti-inflammatory) and a long-acting beta agonist (or LABA, a drug that causes your airways to widen). The drug strengths are always written with the ICS first, then a slash, then the LABA (for example, 100/25). Here's a look at what each product contains:
Breo (per inhalation) 100/25 or 200/25
ICS: fluticasone furoate, 100 mcg or 200 mcg (mcg = micrograms)
LABA: vilanterol, 25 mcg
Symbicort (per inhalation) 80/4.5 or 160/4.5
ICS: budesonide, 80 mcg or 160 mcg
LABA: formoterol, 4.5 mcg
Both ICSs and both LABAs work the same way in the body, but they differ in potency and duration of action.
Key Terms Sidebar!
Potency is a way to compare drugs based on the amount of drug needed to produce a certain clinical effect. For example, the drugs Lipitor and Crestor both work the same way to lower cholesterol levels; however, lowering cholesterol by 20% might require 10-20 mg of Lipitor, but only 5-10 mg of Crestor. We would say that Crestor is more potent than Lipitor, because less drug is required to produce the same effect.
Duration of action, as you'd expect, is the amount of time the drug exerts its clinical effects. Drugs with longer durations of action work for more time and need to be taken less often. Drugs with shorter durations of action work for less time and need to be taken more often.
Breo vs Symbicort
Breo comes in two strength combos, 100/25 and 200/25. Breo is dosed at one inhalation per day, so the 200/50 dose you referred to in your question could only be achieved with two inhalations, and that'd be too high of a dose. Both drugs in Breo are very long acting, and continue to work for 24 hours. Because of this, multiple doses of Breo would risk an overdose of the LABA component, which can cause cardiovascular side effects like heart palpitations and dizziness.
Symbicort also comes in two strength combos, 80/4.5 and 160/4.5. The two drugs found in Symbicort, however, have a lower potency and shorter duration of action than the two in Breo. As a result, and as you mentioned, Symbicort needs to be dosed at two inhalations twice a day to produce a similar level of control as one inhalation once a day with Breo.
Dosages and Side Effects
This difference can have effects beyond just convenience. While the recommended dose of each product will have a similar clinical effect, Symbicort requires a lot more drug be taken to get there. With some drugs (inhaled steroids included), a larger dose might produce a slightly greater desired effect, but a much greater undesired, or "side" effect.
Inhaled corticosteroids, for example, suppress the local immune system along the path of the inhalation -- that is, from your mouth to your lungs. While this is exactly what we want in the lungs to control the inflammation there, this effect in the back of the mouth and throat can allow invasive microorganisms to go wild, since there are less immune cells around to check them. The more medication exposure, the greater chance you'll develop a nasty thrush infection. Rinsing and spitting after using either of these products helps reduce the amount of steroid that sits in the back of your mouth, reducing your risk of infection.
While I can't comment on the decision your pulmonologist made without more information, make sure you let them know if you're having trouble with side effects (like thrush) or with the number of doses required with Symbicort. This is especially important if you have trouble using the Symbicort inhaler. Since it is an aerosol inhaler, the dose sprays out when you actuate the device, whether you're inhaling or not. For some patients, it can be difficult to coordinate the pressing of the inhaler and the act of inhaling. This may be because of difficulties with motor control in the hands, arthritis, muscular weakness, difficulty breathing, or all of these. Regardless of the reason, the result is the risk of the full dose not being delivered.
Breo, on the other hand, is a dry-powder inhaler. When you click the device to activate the dose, the medication only comes out when you put your mouth on the device and inhale it. This allows you to prepare your dose and inhale it when you're ready. It may not seem like a big difference, but if you're affected by this issue, the dry powder inhaler can be kind of a miracle.
As always, make sure you keep your doctor aware of how you're doing with the medication, and don't be afraid to bring up problems you encounter. The point of these medications is to make life easier for people with asthma and COPD, not add to your worries.