Maraviroc: FDA Approved Drug

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Abstract

This paper aims at describing the Maraviroc drug that is approved by the FDA. Besides that, the paper is aimed at analyzing how the drug physiologically operates or works based on the mechanisms of human biology. The paper will cover how the mechanisms correspond to the biological activity, side effects, utility, and the experience with HIV aids patients. To manage a drug, one has to consider the patients’ outcomes and response toward the drug. Again, the drug itself has to be managed to achieve its intended goal. Therefore, the drug must be monitored closely in the market in order to investigate any adverse reactions or resistance.

FDA

Food and drugs administration is a body that scientifically endorses the usage of a given drug to cure human diseases. This drug must be approved before being released to the market. Besides that, this body closely monitors the welfare of that drug in the market and its side effects. Maraviroc (Selzentry) got FDA approval in 2007 for the healing or suppressing of CCR5-tropic HIV-1. This approval was prescribed for the experienced adult patients. Maraviroc is prescribed and can be used together with other antiretroviral treatments. However, Maraviroc does not heal HIV aids. Besides that, it does not stop the spread and contamination of the virus to healthy individuals.

HIV Virus

HIV is a virus that is composed of RNA molecules, the enzyme, and has got the reverse transcriptase enzyme that enables it to change its mechanism of replication. This virus cannot replicate or multiply unless it enters into the DNA of another organism. In order for this virus to replicate, it must seek shelter in the human host CD4 cell. In the host CD4 cells the virus implant itself into the first receptor which is the surface of the CD4 cell and then into the second receptor. This second receptor is either CCR5 or CXCR4. However, at the beginning of infections, most HIV strains use CCR5.

Patient Version: Selzentry (Maraviroc)
Brand Name: Selzentry
Generic Name: Maraviroc
Drug Class: Entry and Fusion Inhibitors (CCR5 antagonist)

Introduction

This FDA body has approved many drugs in connection to prevention, treatment, and curing of various diseases infecting or affecting human beings. Some of these drugs include Aptivus (tipranavir) and Selzentry (maraviroc) for HIV aids among others. For my part, I have decided to choose Selzentry which is also marketed as Celsentri outside the USA. This drug is an entry competitive inhibitor that fuses with the cells in order to inhibit the infected cells from affecting other cells. Therefore, it is used to suppress HIV aids in human beings or to slow down the process of infection but it does not fully cure the disease. Maraviroc is an antiretroviral drug for adults (with CCR5-tropic HIV-1).

Before I address the management, dosage, and side effects of maraviroc, it is good to understand the mechanism, pharmacology, and how the CD4 cells are affected by the HIV virus. After that, the mechanism of how maraviroc works will be understood.

The immune system in the body is facilitated by the blood. In the blood, there are the erythrocytes and leukocytes/lymphocytes. Leucocytes are the white blood cells that defend the body against foreign pathogens. Leucocytes work in conjunction with leucocytes. I am going to concentrate on the leucocytes and their associated cells of the immune system. T cell is a component of white blood cells or leucocytes that are involved in defending the body against foreign pathogens through the immune system.

T cell itself is a lymphocyte and there are more than 40% of lymphocytes in our blood system. T cells coordinate with other cells of the body’s immune system to fight viruses, bacteria, and fungi. Besides that, T cells are manufactured in the bone marrow but migrate in the thymus gland to mature. T cells branch into three groups of more cells. These include CD4+ cells that are also referred to as Helper T cells because they help other cells in the blood system to destroy pathogens. Other cells are CD8+ cells and killer T cells. CD4+ cells are the determinant of the fitness of an individual infected or affected by the HIV virus.

The reason why these CD4+ cells are the determinants of the health of a person is that they are the targets of the HIV virus and it is through the counting of these cells that the health status of an individual can be analyzed and the degree of the infection. After knowing the number and composition of CD4 cells, one can know when to start ant-HIV remedies and when to start prophylaxis measures to prevent opportunistic infections. This is because CD4 cells are the ones that send signals to the body’s immune system so that natural killer cells, interleukins, or suppressive cells can start acting on the virus. Since CD4 cells are the exact targets of HIV aids if this signal is not detected this virus gradually erode the CD4 cells making them decrease in numbers such that the patient now becomes affected by the disease and this is worsened by opportunistic infections such as tuberculosis, malignant tumor, malaria, pneumonia, and typhoid.

Actually, the normal number of CD4 cells is supposed to be from 600 and above per cubic millimeter of blood. The infection starts when the CD4 cells drop below 200 cells per cubic millimeters of blood. The prophylaxis measures should start when you realize that CD4 cells are 200 per cubic millimeters of blood. But drugs for other opportunist infections must be prescribed after diagnosis even if CD4 cells are not less than 200.

Chemical Composition and Structures

Maraviroc is composed of CYP3A inhibitors e.g. nefazodone. These inhibitors may be combined with a CYP3A that is used as an inducer. Other types of inhibitors may be included in the composition. For example, enzyme inhibitors like protease. The chemical composition of these inhibitors is ketonised onazole (ketoconazole), clarithromycin, and itraconazole.

Maraviroc has a composition of active ingredients and inactive ingredients (filler material). Inactive ingredients are grouped into two; Tablet film coat composition and Tablet inner core composition. The Tablet inner core composition includes dibasic anhydrous calcium phosphate, microcrystalline cellulose, and magnesium stearate, and sodium starch glycolate. On the other hand, the Tablet film coat composition includes polyvinyl alcohol, FD&C blue Aluminum Lake, macrogol 3350 (polyethylene glycol), talc, Soya lecithin, and titanium dioxide.

The active ingredients include the Maraviroc itself.

Physiological Reaction and Mechanism (How the Drug Works Based on the Mechanisms of Human Biology)

Maraviroc is an antiretroviral drug that binds to the antigen-presenting cells hence acting as the chemokine receptor. Therefore, it acts in a way to stop the HIV virus from entering into the CD4 T cells that are not infected (acts as an HIV entry inhibitor). Therefore, Maraviroc is a competitive inhibitor. Maraviroc is synthesized in a manner that can hinder HIV viral infection of CD4+ T cells by inhibiting CD4 cell chemokine receptor 5 that is abbreviated as CCR5.CCR5 is a coco-receptor that aids in entries of HIV aids in the cells (John L 2006).

According to Pfizer, maraviroc is an inhibitor that hinders HIV from entering leucocytes. It is in leucocytes that the virus replicates. This process involves confusing the cell’s DNA where it starts the synthesis of HIV single-stranded RNA into DNA. This leads to outnumbering the CD4 cells of the patient hence lowering the immune system. According to LaMattina John, cells chemokine receptor 5 can hinder the entry of the HIV virus to the cell instead of fighting it inside the body leucocytes. By blocking the entry, CCR5 antagonizes the virus from replicating itself. This instead retrogresses the process of virus replication. Therefore, maraviroc can reduce the chances of the HIV virus-producing more copies of the virus.

In physiological breakdown, Maraviroc is metabolized in the liver using cytochrome P450. The terminal half-life is expected to be between 15 and 18 hours at the stable state. Apart from the liver breakdown of Maraviroc, about 27 % of Maraviroc excretion is cleared through the renal pathway as urine. However, slight clearance occurs through perspiration, defecation, and sweating.

Administration

Maraviroc or Selzentry is an oral dose that is packed in 150 mg and 300 mg tablets or even in 600mg. It may be swallowed with or without food. It is supposed to be taken twice a day although doctors can change this dosage accordingly. This is because Maraviroc is prescribed together with other drugs for opportunistic infections (Nelson M and Fatkenheuer, 2007). Some other drugs that can be taken by the patient during medication of maraviroc can increase the rate of reaction in the body. For example, CYP3A inhibitors increase the speed of breaking down the maraviroc molecules. After swallowing the drug, maraviroc is metabolized by the Karpa cells in the liver (Goodrich J and Dejesus, 2005).

How These Mechanisms Relate to the Biological Activity, Utility, and Side Effects

Side effects are negative outcomes of the drugs that are not expected in the processing of treatment or prevention. But the overall effects of a drug are the determining factors as to whether it will be approved. When Maraviroc is administered to control HIV virus replications, the metabolic process occurs in the liver. Therefore, some side effects such as liver toxicity may result in some patients. This happens often when the patient has liver problems or h or she is taking a lot of alcohol.

Other features are specific hypersensitivity-like symptoms. These symptoms are body rashes and elevation numbers of leucocytes such as eosinophils. Besides that, an increase in Immunoglobin E titer may occur before the development of liver toxicity. Therefore, patients undergoing Maraviroc medication should be monitored closely.

While carrying out the clinical trials of Maraviroc, patients receiving this drug were diagnosed with cardiovascular problems such as heart attack. Due to immunological reactions, some blood vessels may be forced to expand or contract. In the case of coronary arteries, dialysis can lead to heart failure in some patients. However, this is a rare case. In addition to that, FDA has authorized the drug to be used keenly in patients who have got higher chances of cardiovascular infections.

Besides cardiovascular infections, Maraviroc binds the co-receptors of CCR5 where it inhibits the infected cells from infecting other cells. Unfortunately, CCR5 co-receptors are located in the cells of the immune system where they can cause infections or malignant tumors. But all the above are minor side effects. However, some common side effects that are found in the patients using Maraviroc are cough, dizziness, hypotension, stomach upset, muscle and joints ailments, while some patients have a fever, others have colds and rashes. Much of Maraviroc is cleared through renal pathways, patients with renal or kidney failure may face the problems of Maraviroc concentrating in the renal arteries. This is worsened by the failure of nephrites. However, dialysis may help to save the situation.

Clinical trials have been tested on the Maraviroc drug but clinical resistance has not been fully analyzed. However, viral tropism that leads to virology failure has been detected. Another side effect is IRS (Immune reconstitution syndrome) that is a minor occurrence. Having noted the side effects, patients are supposed to be monitored closely when on medications because of effects that occur in the immune cells due to CCR5-antagonism.

Safety Precautions

Maraviroc is supposed to be used by adults only who are HIV positive and not people below the age of 17 (Gulick M and Marks K, 2004 ). As mentioned earlier, patients with liver dysfunction, cardiovascular problems, Hepatitis B or C, kidney failure should be monitored closely when under medication. Maraviroc (CCR5 Antagonist) is best recommended for naïve patients who actually tolerate it. However, Maraviroc is not as effective as Efavirenz. Maraviroc (CCR5 Antagonist) works better toward the HIV aids after about six months in two phases.

When under Maraviroc medication, patients are not supposed to take drugs or products that have John’s Wort (hypericum perforatum). This is because Hypericum perforatum reduces the levels of Maraviroc in the blood system. By lowering the chemical level of Maraviroc, the drug might not work effectively to fight the CCR5-tropic HIV pandemic. It is easier to store Maraviroc since it requires a room temperature of Store 15◦Cto 30◦C. Even if there is a person who is suffering from the same disease, it is not good to share, prescribe, or treat a condition that was not mandated by your doctor. This is because Maraviroc may harm them since the dosage is not prescribed by the expert.

Patients should be able to detect early symptoms of allergies. Before serious complication arises minor side effects act as an indicator of early complications. For example, patients may experience allergic reactions before major complications e.g. liver toxicity or cardiovascular problems.

Maraviroc and Food Interactions

After clinical trials and research,¹ Maraviroc has been shown to change the concentration and exposure when it is administered with other antiretroviral drugs such efavirenz and lopinavir/ritonavir. Therefore, doctors are required to change the dosage prescription of Maraviroc. Due to this effect, Maraviroc is supposed to be prescribed by the physicians alone and it should not be sold across the counter.

Summary

The advantages of using Maraviroc are that it is an oral dose found in form of tablets and occurs in different milligrams. Maraviroc (selcentry) can be taken with or without food. Therefore, it does not have an adverse effect on the digestive system. It is easily broken down or metabolized faster, hence easier to start functioning after taking. Its prescription period is shorter and within six months, patients can tell the positive outcomes.

Maraviroc reacts effectively in the body system of a human being. Since it has both active and inactive ingredients, it is a good inhibitor and it easily competes with the HIV-aids virus thus preventing more infection to other cells. Again, Maraviroc can be taken while the patient is taking other drugs for opportunistic infections. Maraviroc can easily be eliminated in the body within a very short period of time through renal excretion.

The demerits of Maraviroc are that it does not cure or heal the pandemic. It only suppresses the rate of replication of the virus. Maraviroc must be mixed with other inducers and inhibitors but this is a common feature for all HIV virus drugs. They must be integrated in order to be effective and to avoid resistance to the virus because it keeps on mutating. Other demerits are the side effects that occur after taking the drug. Market-wise, Maraviroc is good since many patients are giving positive outcomes after using it but it is a bit expensive. However, Maraviroc generics are affordable even to the poor and are effective.

Maraviroc has been shown to change the concentration and exposure when it is taken together with other antiretroviral drugs such efavirenz and lopinavir/ritonavir. Therefore, doctors are required to change the dosage prescription of Maraviroc. Due to this effect, Maraviroc is supposed to be prescribed by the physicians alone and it should not be sold across the counter.

Conclusion

After establishing the mechanisms and management of the FDA drug (Maraviroc) and how it works to mitigate the HIV aids infection, I have discovered that Maraviroc is a good prescription for the pandemic. However, there are some minor side effects but the advantages of Maraviroc to the patients outweigh the demerits. This is because Maraviroc is well tolerated by HIV aids patients and it lowers the patients’ level of HIV infections in ten days. This is highly visible in positive patients with asymptomatic HIV aids infection (Rio de Janeiro, 2007). However, it is the work of the patient to inform the doctor about his/her conditions, drugs under medication, and the outcomes that arise after starting the dosage.

Reference

Fatkenheuer, Nelson and KonourinaI (2006), Maraviroc effective against HIV aids Aspen Publishers HIV aids and new updates. Web.

Journal of the American Medical Association Aspen Publishers Maraviroc composition and ingredients. Web.

M Gulick and Marks K (2004), Antiretroviral drugs for HIV Infection University Academic Press Patients and medical care. Web.

Research and clinical trials of Maraviroc. 2007. Web.

Smith, G P (2004), article in New England Journal of Medicine Articles Vol. 279, Issue 3,

Footnotes

Clinical trials and results for Maraviroc has been positive and hopeful. Web.

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