pentobarbital will decrease the level or effect of pimavanserin samhälle affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Avoid coadministration if possible. Datorskärm for reduced pimavanserin efficacy. An increase in pimavanserin dosage may be needed.pentobarbital will decrease the level or effect of estrogens esterif