Generality
Allopurinol is an active ingredient used to counteract the formation of uric acid .
More specifically, allopurinol belongs to the group of anti- gout drugs since it is used in the treatment of gout, but also in the treatment of all those disorders caused by the presence of excessive levels of uric acid in the body.
In order for it to carry out its therapeutic action, allopurinol must be taken orally . In fact, it is available in the form of tablets in which the active ingredient can be contained in different concentrations (usually, 100 mg, 150 mg and 300 mg).
Allopurinol-based medicines can only be dispensed upon presentation of a repeatable prescription .
Examples of Medicinal Specialties Containing Allopurinol
- Allopurinol DOC Generici®
- Allopurinol Molteni®
- Allopurinol Mylan®
- Allopurinol Sandoz®
- Allopurinol Teva Italia®
- Allurit®
- Zyloric®
Therapeutic indications
When is the use of Allopurinol indicated?
Allopurinol intake is indicated in the following cases:
- Gout treatment;
- Treatment of hyperuricemia caused by various disorders and diseases, including:
- Chronic diseases affecting the kidneys (chronic nephropathy);
- Prolonged therapy with diuretic drugs;
- Polycythemia;
- Some types of tumors.
- Treatment of stones or other renal diseases caused by uric acid;
- Prevention of accumulation of uric acid crystals in tissues and prevention of bone lesion formation;
- Prevention of calcium oxalate stone formation when uric acid levels are high.
Furthermore, allopurinol can be used in adults and children with Lesch-Nyhan syndrome or adenine-phosphoribosyltransferase deficiency (this is a particular hereditary enzyme deficiency disorder).
Did you know that ...
A patient is considered hyperuricemic when - after 5 days of hypopuric diet without taking drugs that affect uricemia - uric acid values are higher than 7 mg / dl for male patients and above 6.5 mg / dl for female patients.
Over 9 mg / dl the risk of developing gout is very high and concrete.
Warnings
Warnings and Precautions for the use of Allopurinol
Before taking allopurinol-containing medicines, you must tell your doctor if you are in one or more of the following situations:
- You are suffering from liver and / or kidney diseases;
- You suffer from cardiovascular diseases;
- An acute gout attack is underway;
- You are suffering from diabetes;
- You are suffering from thyroid disorders;
- One is suffering from hemochromatosis (an inherited disorder characterized by an excessive accumulation of iron in the body).
In any case, it is always a good idea to inform your doctor if you suffer, or have recently suffered from any disorder or illness.
Finally, it should be noted that allopurinol could cause side effects that could alter the ability to drive and use machines, therefore, caution should be exercised.
Please note
For the duration of allopurinol treatment it is necessary to stay hydrated and drink plenty of fluids (non-alcoholic).
Pharmacological Interactions
Interactions of Allopurinol with Other Drugs
Because of the drug interactions that may occur, before starting treatment with allopurinol, you must tell your doctor if you are taking, or have recently been taken, drugs such as:
- Immunosuppressive drugs such as 6-mercaptopurine, ciclosporin and azathioprine;
- Vidarabine (an antiviral drug);
- Antiviral drugs used in the treatment of HIV such as didanosine;
- Probenecid (active ingredient used for the treatment of gout and able to increase the urinary elimination of uric acid);
- Salicylates such as acetylsalicylic acid (non-steroidal anti-inflammatory drug and antiplatelet agent);
- Cumarinic anticoagulants (for example, warfarin);
- Phenytoin (active ingredient indicated in the treatment of epilepsy, cardiac arrhythmias and trigeminal neuralgia);
- Anticancer drugs such as bleomycin, doxorubicin, mecloretamine, cyclophosphamide and procarbazine;
- Theophylline- based drugs (one methylxanthine);
- Thiazide diuretics ;
- Antihypertensive drugs such as captopril (an ACE inhibitor);
- Antibiotic drugs such as ampicillin and amoxicillin;
- Diabetes treatment drugs like tolbutamide and chlorpropamide.
In any case, before starting allopurinol therapy, it is necessary to inform your doctor if you are taking - or if you have recently been - drugs or products of any kind, including medicines without a prescription (SOP ), OTC drugs, herbal and herbal products and homeopathic products.
Taking Allopurinol with Food and Drink
During allopurinol therapy it is necessary to avoid the intake of certain foods and beverages, such as:
- Alcoholic beverages and, in particular, beer;
- Foods containing high levels of prune, such as, for example, the heart, tongue, brain, etc.
Side effects
Side Effects Caused by Allopurinol Intake
Although allopurinol is well tolerated in the vast majority of cases, it is nevertheless able to cause side effects, even if not all patients manifest them, or manifest them equally. In fact, each individual responds to the administration of the drug in a subjective manner and different from the others.
However, below are some of the main side effects that could occur during treatment with allopurinol.
Gastrointestinal disorders
During treatment with allopurinol may occur:
- Nausea and vomit;
- Diarrhea;
- steatorrhea;
- Stomatitis.
Skin and subcutaneous tissue disorders
Taking allopurinol could cause the appearance of:
- Skin rash;
- Itch;
- Redness;
- Skin exfoliation;
- Alopecia;
- Hair color changes;
- Stevens-Johnson syndrome or toxic epidermal necrolysis;
- Lyell syndrome;
- Erythema multiforme.
Nervous system disorders
Allopurinol-based therapy could lead to the onset of:
- Headache;
- Drowsiness;
- dysgeusia;
- Ataxia;
- Peripheral neuropathy;
- Seizures:
- Paralysis;
- Coma.
Fortunately, these are very rare side effects.
Blood disorders
Allopurinol-based treatment may cause:
- Aplastic anemia;
- agranulocytosis;
- Leukopenia;
- leucocytosis;
- eosinophilia;
- Thrombocytopenia.
Disorders of the kidneys and urinary tract
Allopurinol therapy could lead to the onset of:
- Kidney failure;
- hematuria;
- Interstitial nephritis;
- Azotemia;
- Xanthine calculations.
Breast and reproductive disorders
Although rarely, allopurinol-based treatment could cause gynecomastia, erectile dysfunction and male infertility.
Eye and vision disorders
Treatment with allopurinol-containing medicines can cause impaired vision, maculopathies and cataracts.
Cardiovascular disorders
When taking allopurinol, the following may occur:
- Hypertension;
- Vasculitis;
- bradycardia;
- Angina pectoris.
Other side effects
Other side effects that may occur during treatment with allopurinol consist of:
- Allergic reactions, even serious, in sensitive individuals;
- General malaise;
- Asthenia;
- Temperature;
- Hyperlipidemia;
- Diabetes mellitus;
- Depression;
- Dizziness;
- Hepatic disorders;
- Myalgia and / or arthralgia;
- Angioimmunoblastic T-cell lymphoma (fortunately, this is a very rare side effect).
Overdose
Symptoms may occur when taking excessive doses of allopurinol, such as:
- Nausea and vomit;
- Diarrhea;
- Dizziness and vertigo;
- Precipitation of crystals in the urine.
Therefore, if allopurinol overdose is suspected or ascertained, it is necessary to go to the nearest emergency room, taking with you the packaging of the medicine taken. Treatment is generally supportive and, if necessary, gastric lavage can be performed with activated charcoal.
Action mechanism
How does Allopurinol work?
Allopurinol performs its hypouricemic action by acting on a particular enzyme: xanthine oxidase . This enzyme belongs to the group of oxidoreductases and catalyzes the transformation of hypoxanthine into xanthine and xanthine in urates and uric acid. Allopurinol is capable of inhibiting xanthine oxidase, therefore, hindering the synthesis of uric acid and consequently reducing its levels within the body.
Furthermore, in some patients, allopurinol is able to depress the biosynthesis of the purines ex novo by inhibiting the hypoxanthine guanine phosphoribosyl transferase with feedback.
Method of use and Posology
How to take Allopurinol
Allopurinol is available as tablets for oral administration in which the active ingredient can be found in different dosages.
The tablets must necessarily be swallowed whole with the help of a little water, preferably after meals or according to the doctor's instructions.
Please note
During allopurinol therapy - especially if performed to combat gout and uric acid kidney stones - it is necessary to take an adequate quantity of liquids that allows the production of at least two liters of urine per day.
The dose of allopurinol to be taken must be established by the doctor for each patient; however, below are the dosages usually used in therapy.
Adults and adolescents aged between 15 and 18 years
The starting dose of allopurinol usually given in adults and adolescents aged 15-18 years is 100 mg a day. After that, the amount of drug to be taken can be gradually increased until the ideal maintenance dose is reached. This dose may vary depending on the patient's condition:
- Mild conditions: the usual dose is 100-200 mg of allopurinol per day.
- Moderately severe conditions: the dosage of allopurinol usually used is 300-600 mg a day, to be taken in divided doses.
- Severe conditions: the usual dose is 700-900 mg of allopurinol per day, to be taken in divided doses throughout the day.
Children and adolescents aged between 6 and 15 years
In children and adolescents with a age of 6-15 years and a body weight of at least 15 kg, the usual dosage is 10-20 mg / kg of body weight per day, to be administered in divided doses throughout the day.
For this category of patients, the maximum administered daily dose is 400 mg of active ingredient.
Children under the age of 6 years
In children under the age of six, allopurinol should not be administered.
Elderly patients and patients with kidney disease
In elderly patients (over 65 years of age) and in patients suffering from kidney problems, the doctor may decide to reduce the amount of allopurinol administered and / or to reduce the frequency of administration.
Did you know that ...
At the start of treatment with allopurinol, your doctor may decide to prescribe concomitant use of anti-inflammatory drugs or colchicine in order to prevent attacks of gouty arthritis.
Pregnancy and breastfeeding
Can Allopurinol Be Taken in Pregnancy and During Lactation?
The use of allopurinol in pregnant women is generally contraindicated, as there are insufficient data to establish its safety in this category of patients.
The use of allopurinol during breastfeeding, on the other hand, should be carried out only in cases of actual need and only under the strict supervision of the doctor, since the active ingredient is excreted in breast milk . However, if necessary, your doctor may advise you to stop breastfeeding to allow therapy to begin.
Contraindications
When Allopurinol Should Not Be Used
The use of allopurinol is contraindicated in the following cases:
- In patients with known hypersensitivity to allopurinol itself or to any of the excipients contained in the medicinal product to be used;
- During, or immediately after, acute attacks of gout;
- In pregnancy, ascertained or presumed to be.
Finally, it is recalled that, in some cases, the use of allopurinol is contraindicated even in patients with severe renal impairment.
Please note
Although allopurinol can be administered in children and adolescents aged between 6 and 18 years, some medicinal products based on this active ingredient cannot be administered in this category of patients due to the presence of excipients whose intake is contraindicated in this age group. Therefore, in case of doubt, it is advisable to consult your doctor and to carefully read the package insert of the medicinal product based on allopurinol prescribed by it.
