Carbapenems can only be given through an intravenous drip, which usually does not cause irritation at the injection site. If you have a severe allergy to penicillin, you generally should not be given a carbapenem. However, many patients with a mild or moderate allergy can tolerate carbapenems.
Alpha-1 adrenergic agonists. Alpha-1 adrenergic agonists stimulate alpha-1 receptors coupled to G proteins and phospholipase C. They can be classified in two groups: those which do not cross the blood-brain barrier and have peripheral effects and those which penetrate into the brain and have mainly central effects. Alpha-1 agonists with peripheral effects.
There are several theories about how, for example, agonists bind to and activate a receptor. 1  Such theories have to explain the various effects of not only agonists, but also antagonists, partial agonists, and even inverse agonists. One such theory that seems to fit the facts rather well is as follows: