Which of the following first line drugs would require dose adjustment in case of renal insufficiency with creatinine clearance below 30 mL/min?

In the management of tuberculosis, the pharmacokinetics of first-line drugs differ significantly based on the patient's renal function. Ethambutol and pyrazinamide are two anti-tuberculosis medications that are specifically impacted by renal insufficiency.

Ethambutol is primarily excreted through the kidneys, and a reduced creatinine clearance can lead to accumulation of the drug in the body, potentially increasing the risk of toxic effects such as ocular toxicity. Therefore, dosage adjustments are necessary for patients with impaired renal function to prevent adverse reactions.

Pyrazinamide, while mainly metabolized by the liver, also has a significant renal excretion component. In cases of renal failure, the drug's clearance may be reduced, warranting a modification in dosing to avoid accumulating levels that could lead to side effects.

In contrast, isoniazid does require monitoring and potential adjustments based on liver function rather than renal. Therefore, it remains unaffected in the context of renal issues to the same extent as the other two.

Since both ethambutol and pyrazinamide need dose adjustment in the case of renal insufficiency, the correct choice reflecting this requirement is appropriately indicated.