Drug Name Methotrexate

At rest, the intracellular concentration of free calcium ions (Ca2+) is kept at 0. 1 ?M (see p. 128 for mechanisms involved). During excitation, a transient rise of up to 10 ?M elicits contraction in muscle cells (electromechanical coupling) and secretion in glandular cells (electrosecretory coupling).
It is effective in alleviating symptoms of dementia in some subtypes of Alzheimer’s disease. Excitation of the parasympathetic division of the autonomic nervous system causes release of acetylcholine at neuroeffector junctions in different target organs. The major effects are summarized in A (blue arrows).

 

Whereas benzodiazepines possessing agonist activity indirectly augment chloride permeability, inverse agonists exert an opposite action. These substances give rise to pronounced restlessness, excitement, anxiety, and convulsive seizures. There is, as yet, no therapeutic indication for their use.
Although benzodiazepines are well tolerated, the possibility of personality changes (nonchalance, paradoxical excitement) and the risk of physical dependence with chronic use must not be overlooked. Conceivably, benzodiazepine dependence results from a kind of habituation, the functional counterparts of which become manifest during abstinence as restlessness and anxiety; even seizures may occur.