Metisoprinol: Formula, Presentation, Indications, Mechanism of Action, Dosage, Side Effects, Warnings, Contraindications and Interactions

It is an alkylamino-alcohol complex of inosine used in the treatment of a variety of viral infections.

Unlike other antiviral agents, it works by modifying or stimulating cell-mediated immune processes rather than acting directly on the virus.

Chemical formula of metisoprinol

  • C52H78N10O17.


  • Tablets: boxed with 20 tablets of 500 mg.
  • Syrup: in a 60 ml bottle and a measuring cup (250 mg of metisoprinol for every 5 ml of syrup).

Indications of metisoprinol

Metisoprinol is an antiviral medication used to control infections caused by the herpes virus such as: cold and facial herpes simplex, genital herpes, and shingles.

It is also used to treat childhood viral rashes such as chickenpox, measles, and rubella.

It is viral infections such as genital warts, rhinopharyngitis of viral etiology, mumps, subacute sclerosing panencephalitis and hepatitis A.

Mechanism of action

Metisoprinol has two complementary and independent mechanisms of action:

Antivirus action

Metisoprinol works by slowing the growth and spread of the virus in the body, preventing viral replication by blocking any unspecified genetic information in the virus cell.

Pro guest action

Metisoprinol has indirect antiviral activity by stimulating the immune response. Before the appearance of infecting viruses, the natural immune response of the organism increases to combat it.

This immunostimulant intervenes both on the cellular component and the humoral component of the immune response.

It stimulates the activity of macrophages, B and T lymphocytes and potentiates the action of some lymphokines, which helps increase the body’s ability to fight these infections.


Metisoprinol is given by mouth 6 times a day (every 4 hours).

In children:

  • From 1 to 12 months: ½ teaspoon should be given.
  • From 1 to 5 years: 1 teaspoon should be given.
  • From 5 to 12 years: 1½ teaspoon should be given.

In adults:

  • In the initial dose, 2 tablets should be administered in the first dose and it is continued with one tablet every 4 hours.
  • In the ponderal dose, 50 to 100 mg per kg per day should be administered, in divided doses every 4 hours.
  • Regarding the duration of treatment, it is recommended for Herpes, to continue the treatment for 7 to 14 days, for the associated treatment of genital condyloma continue the treatment for 14 to 28 days.
  • According to the evolution of the viral picture, the doses may be modified according to the doctor’s criteria.

The maximum dosage is 4,000 milligrams per day.

Side effects of metisoprinol

The most common side effect is increased uric acid levels in the blood and urine. These alterations usually return to their values ​​once treatment is discontinued.

Monitoring of these levels is necessary, which can cause conditions such as gout and kidney stones .

Other observed side effects are transient alterations in the central nervous system, in the digestive system, in liver, cardiovascular and hematological functions.

Warnings and Contraindications

The prescribed dosing regimen should be completed even if symptoms disappear after a few days of treatment.

In case you miss a dose and it is not close to the time of the next dose, you can take the medicine as soon as you remember, continuing with the regular schedule prescribed by the doctor.

Two doses should not be taken at the same time and treatment should not be prolonged beyond the time recommended by the doctor.

It is not recommended for patients with:

  • History of urinary lithiasis.
  • Drop Background.
  • History of hyperuricemia.
  • Nephrolithiasis or kidney disorders.
  • Hypersensitivity to the components of the formula.
  • Hypersensitivity to xanthic derivatives.

This medicine should not be used during pregnancy and lactation.

Although it lacks teratogenic action, its safety during pregnancy and lactation has not yet been established.

Metisoprinol interactions

Clinical experience has shown that there are no alterations in laboratory parameters, with the exception of an increase in serum and urinary uric acid.

Gastrointestinal topicals, antacids, can decrease the absorption of the drug if it is ingested simultaneously.

Generally, it is recommended that medications be taken with an interval of more than 2 hours, between each dose, if possible.

Since the effectiveness of other medications taken simultaneously with metisoprinol, they can decrease intestinal absorption, reducing their effectiveness and in some cases can increase the effects of the medications.