Final answer:
Co-administering lamotrigine with certain drugs can lead to clinically significant increases in concentration, potentially causing toxicity or reduced efficacy. Examples of drugs that can interact with lamotrigine include valproic acid and rifampin.
Step-by-step explanation:
The concentration of lamotrigine may increase significantly if it is co-administered with certain drugs. One example is valproic acid, which is commonly used to treat epilepsy. When taken together, valproic acid can increase the plasma concentration of lamotrigine by inhibiting its metabolism. This can lead to toxicity and adverse effects.
Another example is rifampin, an antibiotic used to treat tuberculosis. Rifampin can significantly decrease the concentration of lamotrigine by inducing its metabolism. This can result in subtherapeutic levels and reduced efficacy of lamotrigine.
It is important for healthcare providers to be aware of potential drug interactions when prescribing lamotrigine, and to adjust the dosage accordingly to avoid concentration changes that could be clinically significant.