Physostigmine causes miosis and spasm of accommodations

FIGURE 77 Physostigmine causes miosis and spasm of accommodations it also lowers intraocular pressure and hence can be used in the treatment of wide-angle glaucoma. 

Atropine is able to oppose these muscarinic effects. In addition, neostigmine, which has both a direct action as well as an indirect action that is mediated by acetylcholine on end-plate nicotinic receptors, may produce muscular fascicula-tion, muscular cramps, weakness, and even paralysis. These effects are not countered by atropine. Furthermore, neostigmine enhances gastric contraction and secretion. Neostigmine itself is metabolized by plasma acetylcholinesterase. 

The therapeutic uses of neostigmine include the treatment of atony of the urinary bladder and postoperative abdominal distention. In addition, it antagonizes the action of /-tubocurarine and curariform drugs. Edrophonium, neostigmine, or pyridostigmine may be used to diagnose myasthenia gravis. Because edrophonium has the shortest duration of action, it is most often used for this purpose. 

Phytonadione is a blood modifier/vitamin K. It promotes hepatic synthesis of active prothrombin (factor II), proconvertin (factor VII), plasma thromboplastin component (factor IX) and Stuart factor (factor X). It is indicated in the management of coagulation disorders due to faulty formation of factors II, Vn, IX, and X due to vitamin K deficiency or interference with vitamin K activity. Oral/parenteral used for treatment of anticoagulant-induced prothrombin deficiency treatment of hypoprothrombinemia secondary to salicylates or antibacterial therapy, or secondary to obstructive jaundice and biliary fistulas, provided bile salts are also given. Parenteral used for treatment of hypoprothrombinemia secondary to conditions limiting absorption or synthesis of vitamin K prophylaxis and therapy of hemorrhagic disease of the newborn. 

Vitamin K activity is associated with at least two distinct natural substances, designated as vitamin K, and vitamin Kj. Vitamin K or phylloquinone (phytonadione) is 2-methyl-3-phytyl-l,4-naphthoquinone it is found in plants and is the only natural vitamin K available for therapeutic use. Vitamin K is actually a series of compounds (the mena-quinones) in which the phytyl side chain of phylloquinone has been replaced by a side chain built up of 2 to 13 prenyl units. Considerable synthesis of menaquinones occurs in Gram-positive bacteria indeed, intestinal flora synthesize the large amounts of vitamin K contained in human and animal feces. In animals menaquinone-4 can be synthesized from the vitamin precursor menadione (2-methyl-l,4-naphtho-quinone), or vitamin Kj. Depending on the bioassay system used, menadione is at least as active on a molar basis as phylloquinone. 

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Physostigmine causes miosis and spasm of accommodation it also lowers lOP and hence can be used in the treatment of wide-angle glaucoma (Figure 77). Being lipid soluble, it penetrates into the brain rapidly, raises the acetylcholine concentration, and, in toxic amounts, may cause cholinergic CNS toxicity, which is characterized by restlessness, insomnia, tremors, confusion, ataxia, convulsions, respiratory depression, and circulatory collapse. These effects are reversed by atropine. 

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