The metabolic stability and the reactivity of a library of candidate drug compounds have to be assessed for drug metabolism and toxicological studies. Many methods have been proposed for quantitative predictions in drug metabolism; one example of a recent computational method is SPORCalc .  If the chemical structure of a medicinal compound is altered slightly, this could slightly or dramatically alter the medicinal properties of the compound depending on the level of alteration as it relates to the structural composition of the substrate or receptor site on which it exerts its medicinal effect, a concept referred to as the structural activity relationship (SAR). This means that when a useful activity has been identified, chemists will make many similar compounds called analogues, in an attempt to maximize the desired medicinal effect(s) of the compound. This development phase can take anywhere from a few years to a decade or more and is very expensive. 
The most common side effects are related directly to alpha-adrenoceptor blockade. These side effects include dizziness, orthostatic hypotension (due to loss of reflex vasoconstriction upon standing), nasal congestion (due to dilation of nasal mucosal arterioles), headache, and reflex tachycardia (especially with non-selective alpha-blockers). Fluid retention is also a problem that can be rectified by use of a diuretic in conjunction with the alpha-blocker. Alpha blockers have not been shown to be beneficial in heart failure or angina , and should not be used in these conditions.
Nurses use pharmacology on the job to treat their patients and carry out the requests of the patient’s physician. Nurses also use pharmacology to administer drug dosages that the doctor prescribes. Hospitals and clinics prefer nurses who have received training in pharmacology because they receive additional training in drugs and dosing. For example, if nurse administers the wrong dosage of medication to their patients, they could be putting the patients’ lives in danger. Nurses must have a solid understanding of drugs to perform their jobs effectively.