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1.ZOVIRAX HISTORY
How was Zovirax discovered?

Zovirax is a product of GlaxoSmithKline.

Elion working for GlaxoSmithKline in 1979 discovered Zovirax. She was awarded the Nobel Prize for her contribution.

Note: World-drugs.net sells generic version of Zovirax

2.ZOVIRAX FACTS

GlaxoSmithKline (GSK) is a world leading research-based pharmaceutical company with a powerful combination of skills and resources that provides a platform for delivering strong growth in today's rapidly changing healthcare environment.

GSK's mission is to improve the quality of human life by enabling people to do more, feel better and live longer.

GlaxoSmithKline is headquartered in the UK and has operations based in the US; the new company is one of the industry leaders, with an estimated seven per cent of the world's pharmaceutical market.

GSK also has leadership in four major therapeutic areas - anti-infectives, central nervous system (CNS), respiratory and gastro-intestinal/metabolic. In addition, it is a leader in the important area of vaccines and has a growing portfolio of oncology products.

GSK also has a Consumer Healthcare portfolio comprising over-the-counter (OTC) medicines; oral care products and nutritional healthcare drinks, all of which are among the market leaders.

A virus is a small infectious organism that must invade a living cell to reproduce (replicate). The virus attaches to a cell, enters it, and releases its DNA or RNA inside the cell. The virus's DNA or RNA is the genetic code containing the information needed to replicate the virus. The viral genetic material takes control of the cell and forces it to replicate the virus. The infected cell usually dies because the virus keeps it from performing its normal functions. Before it dies, however, the cell releases new viruses, which go on to infect other cells.

Some viruses do not kill the cells they infect, but instead alter the cells' functions. Sometimes the infected cell loses control over normal cell division and becomes cancerous. Some viruses that do not kill the cells they infect leave their genetic material in the host cell where it remains dormant for an extended time (latent infection). When the cell is disturbed, the virus may be able to begin growing again and cause disease.

Viruses usually infect one particular type of cell. For example, cold viruses infect only cells of the upper respiratory tract. Additionally, most viruses infect only a few species of plants or animals; some infect only people.

Viruses are transmitted in a variety of ways. Some are swallowed, some are inhaled, and some are transmitted by the bites of insects and other parasites.

The body has a number of defenses against viruses. Physical barriers, such as the skin, discourage easy entry. Infected cells also make interferons, substances that can make non-infected cells more resistant to infection by many viruses.

Drugs that combat viral infections are called antiviral drugs. Antiviral drugs work by interfering with viral replication. Because viruses are tiny and replicate inside cells using the cells' own metabolic pathways, there are only a limited number of metabolic functions that antiviral drugs can target. In contrast, bacteria are relatively large organisms, commonly reproduce by themselves outside of cells, and have many metabolic functions against which antibiotics can be directed. Therefore, antiviral drugs are much more difficult to develop. Antiviral drugs can be toxic to human cells. Viruses can develop resistance to antiviral drugs.

Antibiotics are not effective against viral infections, but if a person has a bacterial infection in addition to a viral infection, an antibiotic is often necessary.

Probably the most common viral infections are those of the nose, throat, and airways. These infections include sore throat, sinusitis, the common cold, and influenza. Doctors often refer to these as upper respiratory infections (URIs). In small children, viruses also commonly cause croup and inflammation of the windpipe (laryngitis) or other airways deeper inside the lungs.

Other common viral infections are caused by the herpes viruses. Eight different herpes viruses infect people. Three of these—herpes simplex virus type 1, herpes simplex virus type 2, and varicella-zoster virus—cause infections that produce blisters on the skin. Another herpesvirus, Epstein-Barr virus, causes infectious mononucleosis. Cytomegalovirus is a cause of serious infections in newborns and in people with a weakened immune system. It can also produce an illness similar to infectious mononucleosis in people with a healthy immune system. Human herpesviruses 6 and 7 cause a childhood illness known as roseola infantum. Human herpesvirus 8 has been implicated as a cause of cancer (Kaposi's sarcoma) in people with AIDS.

All of the herpesviruses cause lifelong infection because the virus remains within its host cell in a dormant (latent) state. Sometimes, the virus reactivates and produces further episodes of disease. Reactivation may occur rapidly or many years after the initial infection.

How does Zovirax work?

Zovirax tablets contain the active ingredient acyclovir, which is an antiviral medicine used to treat infections with herpes viruses.

The herpes viruses include the viruses that cause cold sores and genital herpes (herpes simplex 1 and 2) and the virus that causes chickenpox and shingles (varicella zoster or herpes varicellae). Acyclovir works by stopping these herpes viruses from reproducing and infecting more cells in the body.

In this herpes simplex virus-infected human cell, the acyclovir molecules enter the cell and are converted to acyclovir monophosphate by the herpes simplex virus enzyme thymidine kinase (TK). Enzymes in the human cell add two more phosphates to eventually form the active drug acyclovir triphosphate. The acyclovir triphosphate competes with 2-deoxyguanosine triphosphate (dGTP) as a substrate for viral DNA polymerase as well as acting as a chain terminator. In actual infection, the herpes simplex virus releases its naked capsid that delivers DNA to the human nucleus; the active drug acyclovir triphosphate exerts its action on the viral DNA located in the nucleus.

The activated acyclovir then works by blocking the action of a viral enzyme called DNA polymerase.

The herpes viruses need the DNA polymerase enzyme to copy their genetic material from RNA to DNA. This process is necessary for the viruses to multiply and continue to survive. By blocking the action of DNA polymerase, Zovirax prevents the herpes viruses from multiplying. This controls the infection and helps the immune system to deal with it.

Zovirax is taken by mouth to treat herpes infections that cause chickenpox and shingles. Zovirax is also taken by mouth to treat genital herpes and other herpes simplex infections of the skin and mucous membranes, and to prevent these infections coming back in people who suffer recurrent infections.

4.ZOVIRAX EFFECTIVENESS
When is Zovirax best taken?

The pharmacokinetics of Zovirax after oral administration has been evaluated in healthy volunteers and in immunocompromised patients with herpes simplex or varicella-zoster virus infection. It was observed that the average oral bioavailability of Zovirax is 10 to 20%.

In one multiple-dose, crossover study in healthy subjects, it was shown that increases in Zovirax concentrations were less than dose proportional with increasing dose. The decrease in bioavailability is a function of the dose and not the dosage form.

There was no effect of food on the absorption of Zovirax; therefore, Zovirax tablets may be administered with or without food.

5.ZOVIRAX EFFECTS ON SPECIAL POPULATION
How do different people react to Zovirax?

Adults with Impaired Renal Function: The half-life and total body clearance of Zoviraxare dependent on renal function. A dosage adjustment is recommended for patients with reduced renal function.

Geriatrics : Acyclovir plasma concentrations are higher in geriatric patients compared to younger adults, in part due to age-related changes in renal function. Dosage reduction may be required in geriatric patients with underlying renal impairment.

Pediatrics: In general, the pharmacokinetics of acyclovir in pediatric patients is similar to that of adults. Mean half-life after oral doses of 300 mg/m 2 and 600 mg/m 2 in pediatric patients ages 7 months to 7 years was 2.6 hours (range 1.59 to 3.74 hours).

6.ZOVIRAX EFFECTS ON MEDICAL CONDITIONS
How does Zovirax affect your existing condition/ailment?

Zovirax should not be used in patients with decreased kidney function.

7.OTHER/ALTERNATE USES OF ZOVIRAX
What else does Zovirax treat?

Zovirax treats certain types of viral infections, specifically herpes infections. Zovirax will not cure herpes infections; it will help the sores heal faster and help to relieve the pain or discomfort. Sometimes Zovirax is given to help prevent the infection from coming back. Zovirax also treats shingles and chickenpox infections.

8.ADVERSE/SIDE EFFECTS of ZOVIRAX
What are the side effects of Zovirax?

Herpes Simplex:

Short-Term Administration : The most frequent adverse events reported during clinical trials of treatment of genital herpes with Zovirax 200 mg administered orally 5 times daily every 4 hours for 10 days were nausea and/or vomiting in 8 of 298 patient treatments (2.7%). Nausea and/or vomiting occurred in 2 of 287 (0.7%) patients who received placebo.

Long-Term Administration : The most frequent adverse events reported in a clinical trial for the prevention of recurrences with continuous administration of 400 mg (two 200-mg capsules) 2 times daily for 1 year in 586 patients treated with Zovirax were nausea (4.8%) and diarrhea (2.4%). The 589 control patients receiving intermittent treatment of recurrences with Zovirax for 1 year reported diarrhea (2.7%), nausea (2.4%), and headache (2.2%).

Herpes Zoster : The most frequent adverse event reported during 3 clinical trials of treatment of herpes zoster (shingles) with 800 mg of oral Zovirax 5 times daily for 7 to 10 days in 323 patients were malaise (11.5%). The 323 placebo recipients reported malaise (11.1%).

Chickenpox : The most frequent adverse event reported during 3 clinical trials of treatment of chickenpox with oral Zovirax at doses of 10 to 20 mg/kg 4 times daily for 5 to 7 days or 800 mg 4 times daily for 5 days in 495 patients was diarrhea (3.2%). The 498 patients receiving placebo reported diarrhea (2.2%).

Observed During Clinical Practice : In addition to adverse events reported from clinical trials, the following events have been identified during post-approval use of Zovirax. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to their seriousness, frequency of reporting, potential causal connection to Zovirax, or a combination of these factors.

General: Anaphylaxis, angioedema, fever, headache, pain, peripheral edema.

Nervous : Aggressive behavior, agitation, ataxia, coma, confusion, decreased consciousness, delirium, dizziness, encephalopathy, hallucinations, paresthesia, psychosis, seizure, somnolence, tremors. These symptoms may be marked, particularly in older adults or in patients with renal impairment.

Digestive : Diarrhea, gastrointestinal distress, nausea.

Hematologic and Lymphatic : Anemia, leukocytoclastic vasculitis, leukopenia, lymphadenopathy, thrombocytopenia.

Hepatobiliary Tract and Pancreas: Elevated liver function tests, hepatitis, hyperbilirubinemia, jaundice.

Musculoskeletal : Myalgia.

Skin : Alopecia, erythema multiforme, photosensitive rash, pruritus, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria.

Special Senses : Visual abnormalities.

Urogenital : Renal failure, elevated blood urea nitrogen, elevated creatinine, hematuria.