Brief Answer:
The smallest dose is 25 mg and maximum dose is 200 mg for Lamotrigine

Detailed Answer:
Dear Suzanne,
Thanks for using Healthcaremagic.

I read your query and understand your concerns.

First of all I am sorry to inform you that the website does not prescribe/provide any medication as prescription rights varies from place to place. In addition every medical council/regulating authorities prohibits the online prescription of medication and that rules out any possibility of getting medication from website. In other words seeing medicine without seeing patient personally is unethical and this website follows the same principle.

This website intends to provide the second opinion in variety of medical conditions. In addition doctor over here can advice you about the right decision and right treatment when patients finds himself lost between the local health professionals.

Now regarding bipolar disorder I like to inform you that if you more depression the Lamotrigine is excellent option for treatment and prophylaxis of bipolar depression. Most patient do respond in dose range of 50-100 per day but the minimum effective dose is 25 mg and maximum limit is 200 mg per day. If you are taking any other medication affecting metabolism of lamotrigine you may need different dose.

I hope this helps you.
If you have any further query, I would be glad to help you.
If not, you may close the discussion and if possible you may rate the answer for my future patients.
In future if you wish to contact me directly, you can use the below mentioned link:
http://doctor.healthcaremagic.com/doctors/dr-ashok-kumar/67386
Thanks and regards.

---