The mediation of olanzapine in the central nervous system by P-GP means that any other substance or drug that interacts with P-GP increases the risk for toxic accumulations of both olanzapine and the other drug.Olanzapine is a potent antagonist of the muscarinic M3 receptor, which may underlie its diabetogenic side effects. Additionally, it also exhibits a relatively low affinity for serotonin 5-HT1, GABAA, beta-adrenergic receptors, and benzodiazepine binding sites.The antagonistic effects of olanzapine at 5-HT2c, histaminergic H1, and muscarinic M3 receptors have been implicated in weight gain.The mode of action of olanzapines antipsychotic activity is unknown. It may involve antagonism of dopamine and serotonin receptors. Antagonism of dopamine receptors is associated with extrapyramidal effects such as tardive dyskinesia (TD), and with therapeutic effects. Antagonism of muscarinic acetylcholine receptors is associated with anticholinergic side effects such as dry mouth and constipation; in addition, it may suppress or reduce the emergence of extrapyramidal effects for the duration of treatment, but it offers no protection against the development of TD. In common with other second-generation (atypical) antipsychotics, olanzapine poses a relatively low risk of extrapyramidal side effects including TD, due to its higher affinity for the 5HT2A receptor over the D2 receptor.Antagonizing H1 histamine receptors causes sedation and may cause weight gain, although antagonistic actions at serotonin 5-HT2C and dopamine D2 receptors have also been associated with weight gain and appetite stimulation. Pharmacokinetics
Metabolism
Olanzapine is metabolized by the cytochrome P450 (CYP) system; principally by isozyme 1A2 (CYP1A2) and to a lesser extent by CYP2D6.
A subconjunctival bleeding initially appears bright-red underneath the transparent conjunctiva. Later, the bleeding may spread and become green or yellow as the hemoglobin is metabolized. It usually disappears within 2 weeks. Causes
Mechanical
Increased venous pressure (e.g. extreme g-force, straining, vomiting, choking, coughing or strangling) or from straining due to constipation
External pressure changes:Atmospheric pressure changes due to aircraft altitude changes. Mask squeeze from diving without equalizing mask pressure during descent or from diving deeply in water
Eye injury
Head injury
Laser eye surgery or other eye surgery
Zygoma fracture (results in lateral subconjunctival bleeding)
Medical conditions that cause increased venous pressure:
Whooping cough or other extreme sneezing or coughing
Severe hypertension
Medical conditions that affect blood or blood vessels:
Certain infections of the outside of the eye (conjunctivitis) where a virus or a bacterium weaken the walls of small blood vessels under the conjunctiva
Coagulation disorder (congenital or acquired) including Ebola
Acute hemorrhagic conjunctivitis (caused by Enterovirus 70 or Coxsackie A virus)
LeptospirosisSubconjunctival bleeding in infants may be associated with scurvy (a vitamin C deficiency),abuse or traumatic asphyxia syndrome. Diagnosis
Diagnosis is by visual inspection, by noting the typical finding of bright red discoloration confined to the white portion (sclera) of the eye. Management
A subconjunctival bleeding is typically a self-limiting condition that requires no treatment unless there is evidence of an eye infection or there has been significant eye trauma. Artificial tears may be applied four to six times a day if the eye feels dry or scratchy. The elective use of aspirin is typically discouraged. References


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