Miosis drug-induced

Pupil Examination. A meaningful evaluation of pupils after drug-induced mydriasis or miosis is impossible. Pupillary examination, including pupil size and responsiveness, should be undertaken before instilling mydriat-ics or miotics.The presence and nature of direct reflexes as well as the presence or absence of a relative afferent pupillary defect should be recorded. 

Carbachol is used as an ophthalmic agent, in the reduction of intraocular pressure. The drug induces miosis, and is therefore also used to counteract the effects of sympathetic agents in the eye. 

Butorphanol use in patients with head injury may be associated with carbon dioxide retention and secondary elevation of cerebrospinal fluid pressure, drug-induced miosis, and alterations in mental state. As with other opioids, such use may obscure important clinical signs in patients with head injuries. 

Medications with anticholinergic properties induce mydriasis, which can lead to angle closure in pupillary block and plateau iris. Pupillary block may also be induced by drugs that cause miosis.12... 

In the unanesthetized dog, reserpine selectively depresses the sympathetic centers and induces facilitation of the parasympathetic centers in the diencephalon. The latter effect accounts for the bradycardia, miosis, aggravation of bronchial asthma, renal and biliary colic, and ulcerative colitis observed in some patients receiving the drug. 

Table 2 lists some of the effects of antl-Ch s and cholinomimetic drugs on brain function (79-84). Doses of OP compounds that are toxic, but too small to threaten life, produce a variety of clinical manifestations, including miosis, muscular fasclculatlon, and apprehension (85,86). The acute behavioral alterations are usually accompanied by marked desynchronization of the EEG (87). Larger doses of OF compounds—which may induce convulsions, muscular paralysis, and death—cause slowing of the EEG pattern followed by the appearance of spike waves that herald the onset of seizures. Symptomatic recovery Is normally complete within 2-9 wk, at which time the erythrocyte cholinesterase content usually has returned to normal (88,89). 

In consonance with this, the drugs most widely used to treat glaucoma (for example, pilocarpine) are parasympathetomimetics, which induce miosis and... 

Most frequently used in these antagonism tests are reserpine and the benzo-quinolizine derivatives, tetrabenazine and Ro-4-1284. The latter 2 drugs have a more rapid onset of action and a more selective activity on the central nervous systems (CNS) than reserpine. Antagonism by test compounds of the induced hypothermia, ptosis (eyelid closure), miosis (decreased pupil diameter), and sedation is measured either separately or combined. Evidence has been presented [8] that hypothermia antagonism is a better indicator of CNS activity, as ptosis and miosis can be influenced also by drugs with a peripheral action [9]. 

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