Fosfomic - General Information
Fosfomic is a selective alpha 1 antagonist used for treatment of symptoms of prostate enlargement (BPH). It also acts to lower blood pressure, so it is a drug of choice for men with hypertension and prostate enlargement. It works by blocking the action of adrenaline on smooth muscle of the bladder and the blood vessel walls.
Pharmacology of Fosfomic
Fosfomic, classified as a quinazoline, is similar to doxazosin and prazosin. As an alpha-adrenergic blocking agent, terazosin is used to treat hypertension and benign prostatic hypertrophy (BPH). Fosfomic produces vasodilation and reduces peripheral resistance but in general has slight effect on cardiac output. Antihypertensive effect with chronic dosing is usually not accompanied by reflex tachycardia.
Fosfomic for patients
Patients should be made aware of the possibility of syncopal and orthostatic symptoms, especially at the initiation of therapy, and to avoid driving or hazardous tasks for 12 hours after the first dose, after a dosage increase and after interruption of therapy when treatment is resumed. They should be cautioned to avoid situations where injury could result should syncope occur during initiation of terazosin therapy. They should also be advised of the need to sit or lie down when symptoms of lowered blood pressure occur, although these symptoms are not always orthostatic, and to be careful when rising from a sitting or lying position. If dizziness, light-headedness, or palpitations are bothersome they should be reported to the physician, so that dose adjustment can be considered.
Patients should also be told that drowsiness or somnolence can occur with terazosin, requiring caution in people who must drive or operate heavy machinery.
Patients should be advised about the possibility of priapism as a result of treatment with HYTRIN and other similar medications. Patients should know that this reaction to HYTRIN is extremely rare, but that if it is not brought to immediate medical attention, it can lead to permanent erectile dysfunction (impotence).
In controlled trials, terazosin has been added to diuretics, and several beta-adrenergic blockers; no unexpected interactions were observed. Terazosin has also been used in patients on a variety of concomitant therapies; while these were not formal interaction studies, no interactions were observed. Terazosin has been used concomitantly in at least 50 patients on the following drugs or drug classes: 1) analgesic/anti-inflammatory (e.g., acetaminophen, aspirin, codeine, ibuprofen, indomethacin); 2) antibiotics (e.g., erythromycin, trimethoprim and sulfamethoxazole); 3) anticholinergic/sympathomimetics (e.g., phenylephrine hydrochloride, phenylpropanolamine hydrochloride, pseudoephedrine hydrochloride); 4) antigout (e.g., allopurinol); 5) antihistamines (e.g., chlorpheniramine); 6) cardiovascular agents (e.g., atenolol, hydrochlorothiazide, methyclothiazide, propranolol); 7) corti-costeroids; 8) gastrointestinal agents (e.g., antacids); 9) hypoglycemics; 10) sedatives and tranquilizers (e.g., diazepam).
Use with Other Drugs
In a study (n=24) where terazosin and verapamil were administered concomitantly, terazosin’s mean AUC0-24 increased 11% after the first verapamil dose and after 3 weeks of verapamil treatment it increased by 24% with associated increases in Cmax (25%) and Cmin (32%) means. Terazosin mean Tmax decreased from 1.3 hours to 0.8 hours after 3 weeks of verapamil treatment. Statistically significant differences were not found in the verapamil level with and without terazosin. In a study (n=6) where terazosin and captopril were administered concomitantly, plasma disposition of captopril was not influenced by concomitant administration of terazosin and terazosin maximum plasma concentrations increased linearly with dose at steady-state after administration of ter-azosin plus captopril.
HYTRIN capsules are contraindicated in patients known to be hypersensitive to terazosin hydrochloride.
Additional information about Fosfomic
Fosfomic Indication: For the treatment of symptomatic benign prostatic hyperplasia (BPH) and also for hypertension.
Mechanism Of Action: Fosfomic selectively and competitively inhibits vascular postsynaptic alpha(1)-adrenergic receptors, resulting in peripheral vasodilation and a reduction of vascular resistance and blood pressure. Unlike the nonselective alph-adrenergic blockers phenoxybenzamine and phentolamine, terazosin does not block presynaptic alpha(2)-receptors and, hence, does not cause reflex activation of norepinephrine release to produce reflex tachycardia.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Terazosin
Synonyms: Terazosin HCl; Terazosin hydrochloride; Terazosina [Inn-Spanish]; Terazosine; Terazosine [Inn-French]; Terazosinum [Inn-Latin]; Trazosin HCl; Abbott 45975
Drug Category: Antineoplastic Agents; Adrenergic alpha-Antagonists; Platelet Aggregation Inhibitors
Drug Type: Small Molecule; Approved
Absorption: Essentially completely absorbed in man (90% bioavailability).
Toxicity (Overdose): LD50=259.3mg/kg (i.v. in mice)
Protein Binding: 90-94%
Biotransformation: Hepatic. One of the four metabolites identified (piperazine derivative of terazosin) has antihypertensive activity.
Half Life: 12 hours
Dosage Forms of Fosfomic: Tablet Oral
Chemical IUPAC Name: [4-(4-amino-6,7-dimethoxyquinazolin-2-yl)piperazin-1-yl]-(oxolan-2-yl)methanone
Chemical Formula: C19H25N5O4
Terazosin on Wikipedia: https://en.wikipedia.org/wiki/Terazosin
Organisms Affected: Humans and other mammals