Pharmacology: Moclobemide Is Classified As an Antidepressant, Essay

Pharmacology: Moclobemide

Moclobemide is classified as an antidepressant, a MAO (monoamine oxidase) inhibitor. Antidepressants are designed to inhibit the reuptake or reabsorbtion of specific neurotransmitters, increasing the levels of these neurotransmitters around the nerves of the brain (Gbemudu, 2011:1). Neurotransmitters such as serotonin, dopamine and norepinephrine (noradrenaline) are often called 'feel good' chemicals that elevate the patient's mood.

Drug class

A deficit of mood-enhancing chemicals is associated with depression, although there is no single neurotransmitter that is associated with depression alone. Because every patient's biochemistry and history of depression is different, different classes of antidepressants are designed to have different effects on the brain's neurotransmitters and have different indicated uses. For example, selective serotonin reuptake inhibitors (SSRI)s like Prozac prevent the reabsorbtion of the 'feel good' chemical serotonin, just as MAOIs prevent the reabsorbtion of monoamine oxidase. Depression is thought to be caused, in part, by a decrease in the concentration of chemicals in the brain called monoamines. "Monoamines may be broken down by a chemical called monoamine oxidase type A. Moclobemide reversibly prevents monoamine oxidase A from breaking down the monoamines," increasing the concentration of these feel-good chemicals in the brain and alleviating the symptoms of depression (Moclobemide, 2011, Depression Guide). Monoamine oxidase breaks down a number of chemicals that affect mood, including norepinephrine and serotonin (MAOI, 2011, Blue Pages).

Moclobemide is used in treating a variety of types of depression, including mild depression (dysthymia); unipolar depression; bipolar disorder; and also reactive, atypical, agitated, and retarded depression. Moclobemide is also frequently used in the treatment of social phobia (Moclobemide, 2011, Depression Guide). There are two types of MAOIs: A and B. A and B types are differentiated by their substrate specificity. MAO-As inhibit the brain chemical monoaimase approximately 80%, while MAO-Bs approximately 20 to 30%. The inhibition effect of one drug dosage of 200mg is short (a maximum of 24 hours) and reversible.Newer MAOIs are considered an improvement on older monoamine oxidase inhibitors (MAOIs) because they are more selective in the chemicals they target associated with depression and their reversibility (Moclobemide, 2011, Depression Guide).

When prescribed for depression, the patient is usually first prescribed 300 mg/day after meals in 2 divided doses and increased gradually to a maximum dosage of 600 mg/day. (Moclobemide, 2011, Mental Health). It is not uncommon for patients being treated for depression to try multiple medications before the correct drug treatment is determined. When transitioning from a SSRI to an MAOI, a period of at least 4-5 half-lives of the SSRI is required, and for or fluoxetine (Prozac), 5 weeks is suggested for safety reasons (Moclobemide, 2011, Mental Health)

Mechanism of action at the receptor and molecular level

Antidepressants treat the chemical, or biological, sources of depression although they can also be used in conjunction with 'talk' therapy, and a combination of 'talk' therapy and drug therapy is usually prescribed as the most effective treatment for depression. By preventing chemicals that cause an elevated mood from being absorbed, the patient's mood is improved. As SSRIs grew in popularity, MAOIs fell out of favor because of their contraindications with other medications, and also with foods and alcohol. Alcohol and aged cheeses can cause adverse reactions in patients taking MAOIs, while SSRIs do not need to be taken in conjunction with a special diet.

MAOIs garnered a great deal of negative publicity, because there negative side effects were only exposed after they had become widely prescribed. A monoamine, tyramine, is involved in the regulation of blood pressure. The MAO enzyme is blocked from controlling tyramine and if too much tyramine is present, blood pressure can rise sharply, causing a hypertensive crisis, even….....