Contraindications and Warnings
In some patients taking alfuzosin - as is the case with all other a1-antagonists, particularly in patients taking antihypertensive drugs and in elderly patients - a lowering of orthostatic blood pressure may occur, with or without symptoms (the most frequent are dizziness, fatigue and sweating), in the first few hours after alfuzosin administration. In these cases it is advisable to place the patient in the supine position until the symptoms are completely resolved. Furthermore, it is recommended to regularly monitor blood pressure, especially at the beginning of treatment, in order to be able to highlight probable drops in blood pressure values. These phenomena are generally transient, may appear at the beginning of therapy and, as a rule, do not affect the continuation of the processing. However, the patient should be informed of the possibility of these events occurring.
It is recommended to pay particular attention to the administration of alfuzosin to patients who have previously responded with marked hypotension to the use of other alpha blockers, while in individuals who exhibit less pronounced sensitivity to these drugs it is recommended to initiate treatment with alfuzosin by increasing the dose gradually, until the therapeutic dose is reached. The administration of alfuzosin in subjects with severely impaired renal function is strongly discouraged, also due to the lack of clinical data on the safety of this group of patients. the treatment of symptoms of benign prostatic hyperplasia with alfuzosin should be combined with the treatment of heart failure with vasodilators, therefore it is recommended to pay attention to the increased risk of hypotension.
Before starting the treatment of the symptoms of benign prostatic hyperplasia with alfuzosin, it is recommended to carry out all the necessary tests to rule out the presence of a malignant growth in the prostate, also because treatment with alfuzosin can hide these symptoms by delaying the correct diagnosis of the prostate. illness.
Floppy Iris Syndrome (IFIS - "Intraoperative Floppy Iris Syndrome", which is a variant of small pupil syndrome) has developed in some patients previously treated or treated with tamsulosin during cataract surgery. other alpha-1 blockers have occurred in isolated cases and the possibility of a generalized effect of this class of drugs cannot be excluded. Since IFIS may increase procedural complications during cataract surgery, it is recommended that the surgeon, before proceeding with surgery, be aware of any current or previous treatment with alfuzosin or other alpha-1 blockers.
Even in patients who suffer from a congenital QTc interval lengthening, in subjects with a known history of acquired QTc lengthening, and / or who are taking medications known to increase the QTc interval, more care should be taken and investigations made first. starting the administration of alfuzosin.
Alfuzosin is metabolised by the cytochrome P450 enzyme group, namely by the CYP3A4 isoenzyme. Therefore, clinical studies were performed by administering inhibitors of the CYP3A4 isoenzyme together with alfuzosin, to ascertain possible changes in the metabolism of the latter. After the administration of a strong inhibitor of the CYP3A4 isoenzyme, specifically ketoconazole at therapeutic doses of 200 mg / day and 400 mg / day, concomitantly with the 10 mg / day dose of prolonged-release alfuzosin tablets, there was an increase in the maximum plasma concentration of alfuzosin of 2.1 and 2.3, respectively. times the maximum plasma concentration that occurs after administration of alfuzosin alone. Therefore it is recommended to avoid co-administration of alfuzosin and ketoconazole, or other potent inhibitors of the CYP3A4 isoenzyme such as itraconazole or r Tornavir. Clinical studies have been carried out. also carried out on the simultaneous administration of alfuzosin and moderate inhibitors of the CYP3A4 isoenzyme, such as diltiazem, a drug which in this case deserves special attention because of its antihypertensive properties. In fact, the continuous administration of diltiazem at therapeutic doses and of alfuzosin resulted in an increase in the plasma concentration of the latter of about 1.5 times compared to the normal plasma concentration; on the other hand, the maximum plasma concentration of diltiazem was also increased. , even if there were no significant changes in blood pressure. However, since these are two drugs that have antihypertensive properties, it is recommended to avoid their simultaneous administration. The same study also confirmed that administration of alfuzosin at therapeutic doses does not inhibit the activity of most cytochrome P450 isoenzymes.
Other clinical studies have been performed to check the interaction of alfuzosin with some of the drugs most at risk of compromising plasma concentrations due to metabolism by the same enzyme group. From these studies it was noted that co-administration at therapeutic doses of alfuzosin and warfarin or digoxin or hydrochlorothiazide has no influence on the plasma concentration of the two drugs. Conversely, co-administration at therapeutic doses of alfuzosin with cimetidine or atenolol causes a considerable increase in the maximum plasma concentration of alfuzosin, while in the case of atenolol co-administration with alfuzosin causes a considerable lowering of blood pressure, due to the properties antihypertensive of both drugs, therefore it is strongly discouraged.
Pregnancy and breastfeeding
Alfuzosin is not a drug that is normally used in women, but some studies on pregnant animals have been conducted assuming its use in the treatment of hypertension. However, there are no clinical studies on pregnant women. No teratogenic or embryotoxic effects on the fetus were observed in a study in female rats, which were given doses of alfuzosin that exceed the therapeutic doses used in humans by approximately 1200 times. However, a slight prolongation of gestation was observed, but without consequences or difficulties during delivery. The same study observed gestation in rabbits, who were given alfuzosin doses three times higher than the maximum recommended therapy dose in humans; also in this case no teratogenic effects or embryo-fetal toxicity were noted. However, since animal studies cannot 100% simulate the behavior of the drug in the human organism, the use of alfuzosin during pregnancy should only be done when strictly necessary and when the benefits for the mother are greater than possible. dangers to the fetus.
Due to the lack of specific studies, there are no reliable data regarding the secretion of alfuzosin in breast milk, but based on the fact that most drugs are secreted in breast milk it is recommended that particular care be taken when administering alfuzosin to mothers during l "breastfeeding of their children.
Side Effects and Unwanted Effects
As is well known, along with the desired effects, a drug can also cause side or unwanted effects. Although most patients using the drug do not experience any side effects, it is a professional obligation to mention all possible side effects that may occur, making the patient well informed, and prepared - in case an undesirable effect occurs - in the report it promptly to your doctor. The most common side effect that can occur following the administration of alfuzosin is dizziness. Due to the hypotensive effect of the drug, dizziness occurs in about 5% of treated patients.
Another common side effect of alfuzosin is sudden fainting, affecting approximately one percent of treated patients; to prevent this effect from manifesting itself, or in case it does occur, it is advisable not to get up suddenly, not to stay too long on your feet and not to expose yourself excessively to high climatic temperatures; if you were to perceive the signs of fainting, it is recommended to lie down for a few minutes and then, before getting up, to remain seated for another couple of minutes.Other less frequent side effects are those related to the gastrointestinal system, such as constipation, diarrhea, abdominal pain, dyspepsia and nausea; those related to the kidneys and urinary tract, such as increased urine production and the frequent need to urinate; those related to the respiratory system, such as nasal congestion and dyspnea; those related to vision, such as the manifestation of the Floppy Iris Syndrome during cataract surgery; those related to the cardiovascular system, such as tachycardia, arrhythmia, edema, heart palpitations, orthostatic hypotension and peripheral ischaemia. However, all undesirable effects seem to be attributed to the pharmacological properties of alfuzosin and are not permanent but transient, so they tend to resolve over time.
