Ribavirin

Ribavirin is an antiviral drug capable of interfering with the synthesis of nucleic acids (DNA and RNA) of viruses.

Ribavirin - Chemical Structure

It is available in the form of pharmaceutical formulations suitable for oral administration and inhalation administration.

Indications

For what it uses

The use of ribavirin is indicated for:

Treatment of some chronic forms of hepatitis C always in combination with peginterferon alfa-2a or interferon alfa-2a (oral administration);
Treatment of some chronic forms of hepatitis C in HIV-infected patients, always in combination with peginterferon alfa-2a or interferon alfa-2a (oral administration);
Treatment of severe bronchiolitis caused by syncytial virus (inhalation administration).

Warnings

Patients who suffer - or have suffered - from kidney and / or liver problems should inform their doctor before starting treatment with ribavirin orally. This is because such patients may need to be given an antiviral dose reduction or may need to perform certain tests.

In any case, before starting oral ribavirin therapy, patients should undergo blood tests and appropriate controls to determine kidney function.

Patients suffering from heart problems must undergo regular checks, both before starting treatment with ribavirin orally and for the duration of the treatment.

Oral ribavirin can cause anemia, especially in women.

In the event of any type of allergic reaction, treatment with ribavirin should be stopped immediately and the doctor should be contacted immediately.

Because of the dental and gum disorders that ribavirin can cause, patients being treated with this antiviral must undergo regular dental examinations.

Oral ribavirin should not be used in children and adolescents under 18 years of age.

Because it can cause bronchospasm, inhaled ribavirin should be given very carefully in patients with chronic obstructive pulmonary disease or asthma.

If there is a worsening of lung function during ribavirin therapy by inhalation, treatment with the drug should be stopped immediately.

The use of ribavirin by inhalation in children may cause worsening of lung function.

Interactions

HIV patients who have already undergone highly active antiretroviral therapy ( HAART ) should inform their doctor before starting a possible treatment with ribavirin and peginterferon alfa-2a or interferon alfa-2a. This is because the combination of these two therapies can increase the risk of developing lactic acidosis or liver failure.

The simultaneous use of oral ribavirin and didanosine (a drug to treat HIV) should not be performed.

Concomitant administration of azathioprine and ribavirin orally and peginterferon exposes patients to an increased risk of developing severe blood disorders.

In any case, it is advisable to inform your doctor if you are taking - or have recently been taken - drugs of any kind, including non-prescription medicines and herbal and / or homeopathic products.

Side effects

Ribavirin can cause various side effects, although not all patients experience them. This depends on the different sensitivity that each individual has towards the drug. Therefore, the effects are not necessarily all manifested with the same intensity in each patient.

The main side effects that may occur during ribavirin therapy will be briefly listed below.

Blood and lymphatic system disorders

Treatment with ribavirin may cause:

Anemia, ie the decrease in the amount of hemoglobin in the blood;
Leukopenia, ie the decrease in the number of leukocytes in the blood;
Neutropenia, ie the decrease in the number of neutrophils in the bloodstream;
Piastrinopenia, ie the decrease in the number of platelets in the bloodstream;
Enlargement of the lymphatic glands.

Psychiatric disorders

Cases of depression and onset of suicidal thoughts have been reported during treatment with ribavirin and some patients have died. If any symptoms of depression appear, you should contact your doctor immediately.

Furthermore, treatment with ribavirin may cause:

Aggression;
Nervousness;
Anxiety;
Mood changes;
Decreased libido;
Insomnia;
Psychotic disorders;
Mania;
Bipolar disorder.

Nervous system disorders

Ribavirin therapy may cause:

Memory loss;
Migraine;
Numbness;
Peripheral neuropathy;
Burning sensation;
Tremors;
Alteration of the sense of taste;
Drowsiness;
Nightmares;
Dizziness;
Facial paralysis;
Convulsions;
Coma.

Gastrointestinal disorders

Ribavirin treatment may cause:

Diarrhea or constipation;
Nausea;
He retched;
Abdominal pain;
Dyspepsia;
Flatulence;
Pancreatitis;
Stomatitis;
Gastrointestinal bleeding;
Gastric ulcer;
Ischemic colitis;
Ulcerative colitis.

Lung and respiratory tract disorders

Ribavirin therapy can cause coughing, shortness of breath, upper respiratory tract infections, bronchitis, inflammation of the nose and throat, nose bleeds, sore throat, pneumonia, interstitial pneumonia and blood clot formation in the lungs.

Cardiovascular disorders

Treatment with ribavirin may promote the onset of:

Bradycardia or tachycardia;
Heart attack;
Heart failure;
Heart pain;
Inflammation of the membrane that covers the heart (pericarditis);
Heart infections;
Hypertension.

Skin and subcutaneous tissue disorders

Ribavirin therapy may cause:

Itch;
Dermatitis;
Dry skin;
Skin eruptions;
Alopecia;
Urticaria;
Eczema;
Psoriasis;
Photosensitization reactions;
Increased sweating;
Night sweats;
Toxic epidermal necrolysis;
Stevens-Johnson syndrome;
Erythema multiforme;
Angioedema.

Musculoskeletal disorders

Treatment with ribavirin may induce:

Myalgia;
arthralgia;
Bone pain;
Muscle weakness;
Muscle cramps;
Neck and back pain;
Joint inflammation;
Inflammation of the muscles;
Serious muscle damage.

Eye disorders

Ribavirin therapy may lead to the onset of:

Eye pain;
Blurred vision;
Inflammation and dry eye;
Retinal bleeding;
Retinal inflammation;
Corneal ulceration;
Loss of sight;
Retinal detachment.

Hepatobiliary disorders

Treatment with ribavirin may cause changes in liver function, liver failure, inflammation of the bile ducts, fatty liver and liver tumors.

Other side effects

Other side effects that may occur during treatment with ribavirin are:

Allergic reactions, even serious, in sensitive subjects;
Systemic lupus erythematosus;
Changes in renal function;
Urinary tract infections;
Impotence;
Onset of fungal infections;
Ear pain;
Hearing loss;
Temperature;
Fatigue;
Malaise;
Chills;
Loss of appetite;
Sarcoidosis;
Thyroid inflammation;
Diabetes;
Dehydration.

Side effects typical of the administration of ribavirin by the inhalation route

In addition to some of the side effects mentioned above, inhaled ribavirin may also promote the onset of:

Laryngitis;
Pharyngitis;
Dyspnoea;
Bacterial pneumonia;
Apnea;
Thoracic oppression;
Bronchospasm.

Overdose

If you suspect that you have overdosed ribavirin, you should contact your doctor immediately or go to the nearest hospital.

Action mechanism

Ribavirin is effective both against DNA viruses and against RNA viruses.

More in detail, ribavirin performs its antiviral action by inhibiting viral RNA polymerase (the enzyme of viruses responsible for the synthesis of new RNA), blocks the activity of messenger RNA (introducing mutations within it) and blocks the synthesis of nucleic acids (DNA and RNA, in fact).

In addition to having a block in the synthesis of nucleic acids, therefore, there is also a block in the synthesis of viral proteins.

Mode of Use - Posology

Ribavirin is available for oral administration in the form of tablets, hard capsules or oral solution and for inhalation administration as a powder for nebulizer solution.

Below are some indications on the doses of ribavirin usually used in therapy.

Oral administration

During oral ribavirin therapy, it is essential to follow the instructions given by the doctor scrupulously, both as regards the dose of the drug to be taken and the duration of the therapy itself.

Usually, ribavirin should be taken on a full stomach. The doses of antiviral usually used are of 800-1200 mg of drug per day, to be taken in two divided doses. The duration of treatment varies depending on the patient's response to therapy.

Inhalation administration

When administered by inhalation, the dose of ribavirin usually used is 6 g per day to be dissolved in 300 ml of water for injections. The solution thus obtained must be used only and exclusively by inhalation and must be dispensed only and exclusively through the special dispenser. The duration of treatment is usually 3-7 days.

Even in this case, it is still essential to strictly follow the instructions given by the doctor on the dosage and how to use the drug.

Pregnancy and breastfeeding

Because of the serious damage it can cause to the fetus or baby, the use of ribavirin by pregnant women and by breastfeeding mothers is contraindicated.

Furthermore, female patients of childbearing age must adopt adequate contraceptive methods to prevent the onset of pregnancy, both during treatment with ribavirin and for a period of at least four months after the end of the same.

Male patients, on the other hand, must adopt adequate contraceptive methods throughout the duration of ribavirin treatment and for at least seven months after the end of the treatment.

Contraindications

The use of ribavirin is contraindicated in the following cases:

In patients with known hypersensitivity to ribavirin;
In patients with advanced liver disease (when ribavirin is administered orally);
In patients who have suffered from serious heart conditions for less than six months (when ribavirin is administered orally);
In patients with sickle cell disease or thalassemia (when ribavirin is administered orally);
In patients in whom it is necessary to resort to assisted ventilation (when ribavirin is administered by inhalation);
Pregnant;
During breastfeeding.