Pharmacology of Methiocarb - Essay Example

Case study: pharmacology of methiocarb Name: Date: Introduction In this case, a four year old accidentally consumes a poisonous substance. For this incident, the father positively identifies the drug consumed as snail pellets. Snail pellets is a Methiocarb that is used as a pesticide. Methiocarbs are basically carbamates that are used as insecticides to repel birds. As compared to organochlorines, they have a longer effect period and are persistent in crops. The substance however has a limited persistence when taken up by human beings or mammals. This is particularly due to the reversibility of the actions of the chemical. When consumed or if it is contacted by human beings, the chemical displays a number of signs and symptom that reflect its pharmacological action. Key among the symptoms is convulsions and muscle spasm as depicted in the subject. It is challenging to identify the chemical composition of the substance accidentally consumed by a subject in cases where the talking is not audible. However in this case, the composition of the poison consumed is known. In this paper the possible pharmacological effects of the chemical and the symptoms are discussed. It also looks at the medical remedies of the effects of consuming the compound. Chemical composition of Methiocarbs Carbamic acids which are used to make carbamates are a result of a derivation of amines. The illustration of a chemical reaction below shows a reaction where a carbamate is derived from an amine through combining with carbon dioxide. R2NH + CO2 → R2NCO2H From this reaction the ionization of the proton carbamic acid gives rise to a carbamate anion, which is considered as the conjugate base of carbamic acid. The reaction can be illustrated by the chemical equation below. R2NCO2H → R2NCO2- + H+ It is also important to note that carbamates are also made from chloroformamides hydrolysis which is then esterified to give the carbamate. The systematic name of the carbamate that is generically referred to as methiocarb is 3,5-Dimethyl-4-(methylsulfanyl)phenyl methylcarbamate. In commercial production Methiocarb is derived from 4-methylthio-3,5-xylenol and methyl isocyanate. Methiocarb is broken down in the human body by the liver. The compound undergoes sulfoxidation which is the main reaction at this stage but due to the presence of a Phenol group that is cleaved from it by choline-esterase, the compound also undergoes a minor hydroxylation. The result of the reaction is sulfur produced from the sulfoxidation with the possibility of the sulfur being oxidized to produce sulfone. The compound is taken up to the body via different routes. Effects of Methiocarbs on mammals The effects of methiocarb on mammals can be discussed under two possible toxicity effects. The compound can cause acetylcholinesterase inhibition and oxidative stress. Acetylcholinesterase inhibition is the main mechanism of carbamate toxicity. When this inhibition occurs the body’s parasympathetic nervous system is affected. All the functionalities of the body that are coordinated by the parasympathetic nervous system will not occur normally. For instance, the individual will not experience lacrimation. The eyes generally appear dry even if the person intends to cry. The tears cannot show. The parasympathetic nervous system coordinates functions like the production of saliva, defecation and digestion. These are the possible symptoms that will be observed from a subject suffering the effects of acetylcholinesterase inhibition. It is important to note that the actions of the different nervous systems are complimentary to each other. Therefore, the possible effects may not be limited to the coordination of the parasympathetic nervous system. The complementary action of the nervous system will be the main symptoms observed in the case of this form of inhibition. For instance if the main problem caused by the problem is indigestion then the sympathetic nervous system will send signals to the brain to perform a reversal of ingestion. Vomiting in this case is the possible consequence of the action of the parasympathetic nervous system. In the case of consumption of methiocarb by the four year old, the most visible symptoms that can be seen as a result of acetylcholinesterase inhibition are vomiting and diarrhea. This set of symptoms can be explained by the complementary effect of the nervous system. The inhibitors also have an effect on the neuromuscular junction. The result of this action is continued muscular contraction on the subject. The substance can also cause bradycardia. This is a condition in which the heart rate is lowered to extreme levels. The resulting consequences could be weakness which may result in the fainting of the subject. Insomnia is also a major symptom that the boy could display. This is the inability to rest. It is noted that parasympathetic nervous system controls the functions of the body while the body is at rest. The reverse action caused by the inhibitor will not let the body rest and consequently the boy would not go to sleep. Acetylcholinesterase inhibition is likely to cause the body to reduce the production fluids like saliva and tears which are normally produced when the body is at rest. The complementary action of the nervous system however is going to send signals to the body to produce excess of these fluids resulting in the eyes of the patient being overly teary; the amount of saliva produced by the body also goes up. Acute poisoning by this substance could cause death. However, deaths caused by accidental consumptions are rare. This is mainly because methocarb’s acetylcholinesterase inhibition is reversible. Treatment Two types of cholinesterase exist. The compounds exists in the in the red blood cells and the neuromuscular junction. To counter their effect, Anticholinesterases are always administered. The desired action of the drug is to reduce the muscular contraction so as to relieve the patient of the negative effects of the undesired contractions. Neostigmine an acid transferring compound and edrophonium composition are the most likely combination of the drugs that are to be issued to ameliorate the effects of acetylcholinesterase inhibition. These are usually administered with the possible side effects noted beforehand. The main function of these drugs is to unblock the neuromuscular junction. Even though the drugs possess an amount of side effects, their administration is the best possible action plan that will mitigate the effect of acetylcholinesterase inhibition caused by methiocarb ingestion. In the case of jimmy, the Anticholinesterases would be beneficial in unblocking the neuromuscular junction. This would facilitate the relaxation of the muscles from contraction. The side effects that Jimmy is likely to face are directly linked to the blocking of the plasma components from the access to the nicotinic receptor. Efficacy of methiocarb The intention of manufacture of Methiocarb was to produce an insecticide. However, the achievement of this purpose has been limited in degree of success in the research of effective insecticide due to the reversibility in action. For small insects like thrips, the insecticide has achieved a high degree of effectiveness. However as an aerosol used to repel birds the substance has achieved little effectiveness. As a molluscicide, the compound has gained a degree of effectiveness. However, the absorption of the compound must be at high degrees to effectively control the pests. According to information available online, methiocarb did not effectively eliminate the avian pests. Despite being applied as an aerosol, the effect it had on the birds was significantly low. Effects of Brodifacoum Brodifacoum is a 4-hydroxycoumarin anticoagulant compound that affects the coagulation of blood. It main molecular mode of action is the prevention or inhibition of the level of production of vitamin K in the blood. The result of this action is the continued depreciation of the level of prothombin in the blood that is required for purposes of clotting of blood. The effect caused by this substance effectively increases the severity of the condition till the blood of the mammal loses the property to clot. When taken in toxic levels, the substance will cause a severe inability of the blood to coagulate and would to the small blood vessels leakage. When this happens the first organs to be affected are internal organs. Bleeding of the internal organs will cause the subject a great level of shock. Unlike methiocarb, the substance is highly lethal. This is mainly because the substance is a cumulative poison. The process of eliminating the substance from a system is extremely slow. The substance is mainly eliminated in stool and this implies that the normal time taken before defecation has to elapse before the drug can be effectively taken out of the system. In this case if consumed the results would be very detrimental. The substance causes internal bleeding of organs which the symptoms can be shown by the symptoms of progressive shock. The affected subject experiences extreme weakness and this eventually lead to unconsciousness. In most cases the result of this ingestion or uptake of the chemical leads to death. References Brenner, G. M., & Stevens, C. W. (2010). Pharmacology. Philadelphia, PA: Saunders/Elsevier. Clark, M. A. (2012). Lippincott's illustrated reviews. Baltimore, MD: Wolters Kluwer Health/Lippincott Williams & Wilkins. Hacker, M. P., Messer, W. S., & Bachmann, K. A. (2009). Pharmacology: Principles and practice. Amsterdam: Academic Press/Elsevier. Kenakin, T. P. (2006). A pharmacology primer: Theory, applications, and methods. Amsterdam: Elsevier Academic Press. Loose, D. S., & Rosenfeld, G. C. (2007). Pharmacology. Philadelphia: Lippincott Williams & Wilkins. Wanamaker, B. P., & Massey, K. L. (2009). Applied pharmacology for veterinary technicians. St. Louis, Mo: Saunders/Elsevier. Read More