Nicardipine, Nifedipine, and Isradipine are calcium channel blockers that work to decrease systemic vascular resistance and subsequently lower blood pressure. Hydralazine and Sodium nitroprusside are systemic vasodilators, thereby reducing afterload, however can be found to have reflex tachycardia, making them likely second or third line choices. Sodium nitroprusside was previously the first-line choice due to its rapid onset, although now it is less commonly used due to side effects, drastic drops in blood pressure, and cyanide toxicity. Sodium nitroprusside is also contraindicated in patients with myocardial infarction, due to coronary steal. It is again important that the blood pressure is lowered slowly. The initial goal in hypertensive emergencies is to reduce the pressure by no more than 25% the mean arterial pressure. Excessive reduction in blood pressure can precipitate coronary, cerebral, or kidney ischemia and, possibly, infarction.A hypertensive emergency is not based solely on an absolute level of blood pressure, but also on a patients baseline blood pressure before the hypertensive crisis occurs. Individuals with a history of chronic hypertension may not tolerate a "normal" blood pressure, and can therefore present symptomatically with hypotension, including fatigue, light-headedness, nausea, vomiting, or syncope. Prognosis
Severe hypertension is a serious and potentially life-threatening medical condition. It is estimated that people who do not receive appropriate treatment only live an average of about three years after the event.The morbidity and mortality of hypertensive emergencies depend on the extent of end-organ dysfunction at the time of presentation and the degree to which blood pressure is controlled afterward.
Tolcapone, sold under the brand name Tasmar, is a medication used to treat Parkinsons disease (PD). It is a selective, potent and reversible nitrocatechol-type inhibitor of the enzyme catechol-O-methyltransferase (COMT). It has demonstrated significant liver toxicity, which has led to suspension of marketing authorisations in a number of countries. In comparison with entacapone, another nitrocatechol COMT inhibitor, tolcapone has a longer half life (2.9 hours vs. 0.8 hours) and can better penetrate the blood–brain barrier, acting both in the central nervous system and in the periphery. However, entacapone is less toxic for the liver. Medical uses
Tolcapone is used in the treatment of Parkinsons disease as an adjunct to levodopa/carbidopa or levodopa/benserazide medications. Levodopa is a prodrug for dopamine, which reduces Parkinson symptoms; carbidopa and benserazide are aromatic L-amino acid decarboxylase (AADC) inhibitors.Without administration of tolcapone, the beneficial effects of levodopa tend to wear off more quickly, resulting in motor fluctuations. Contraindications
Combining tolcapone with non-selective monoamine oxidase inhibitors such as phenelzine or tranylcypromine is contraindicated. Tolcapone is also contraindicated for people with liver diseases or increased liver enzymes. Side effects
Tolcapone has demonstrated significant liver toxicity (hepatotoxicity) that limits the drugs utility. Entacapone is an alternative, largely since it has a more favorable toxicity profile. The hepatotoxicity can be related to elevated levels of transaminases, but studies have shown that minimal risk exists for those without preexisting liver conditions when their enzyme levels were being monitored.