**3. Catecholamine synthesis or release blockers and oxazolidinone**

The severity of the most frequent used drugs in ICU is moderate to minor. However, the combination of catecholamine synthesis or release blockers with oxazolidinone is contraindicated because it may result in hypertensive crisis, causing headache, palpitation and neck stiffness. Hypertension due to drugs can cause increase of blood pressure level, reduction of antihypertensive drug effectiveness or the worsening of a pre-existing hypertension.

Linezolida is an antibiotic used to treat infections caused by gram-positive bacteria but this drug is also a non-selective and reversible inhibitor of monoamine oxidase (MAO). The inhibitors of this enzyme block the oxidative deamination of three biogenic amines which are norepinephrine, dopamine and 5-hydroxytryptamine. When monoamine oxidase inhibitors (MAOI) are associated with sympathomimetic drugs or foods containing tyramine, hypertensive crisis may occur (Fuzikawa et al., 1999). The hypertensive crises are life-threatening and can also cause damage to susceptible organs as heart, brain and kidneys (Plavnik, 2002).
