Sildenafil drug data and news

---

Chinese Herbal Medicines  16 May 2006
The "herbal viagras" Meng Rong and VG contain sildenafil, and Yixinjiaonang contains tadalafil. Sildenafil and tadalafil are known ... - Consumer Online,

A fairy tale of a drug  May 13, 2006
But in the case of the Pfizer drug, Viagra (sildenafil), no such problems surfaced. Sildenafil belongs to a group of drugs called ... - Malaysia Star,

What do we know about the links between recreational drug use ...  May 15, 2006
...drink enough fluids during a drug-taking session and avoiding dangerous drug combinations, such as GHB with alcohol and poppers with sildenafil (Viagra) or ... - Aidsmap,

Viagra may help children with fatal lung disorder  May 8, 2006
Physicians at The Hospital for Sick Children (SickKids) have found that the drug sildenafil, also known as Viagra, may help children suffering from pulmonary ... - Hospital News,

Recent studies from Germany and the United States add new data to ...  May 8, 2006
Study 1: In infants after cardiac surgery, sildenafil may increase cerebral blood flow, probably due to general endothelial dysfunction after cardiopulmonary ... - Therapeutics Daily (subscription) (press release),

Cialis Is Effective In The Treatment Of Men With Erectile ...  Apr 24, 2006
Viagra® (sildenafil citrate) was the first of the class to be introduced in 1998 and later followed by Levitra® (Vardenafil) and Cialis® (Tadalafil) in 2003 ... - UroToday,

Health Canada Issues Warning of Serious Health Risks Posed By ...  May 7, 2006
...to consumers not to use the non-prescription product, Nasutra, because “it has been found to contain the undeclared ingredient sildenafil (chemical name for ... - Newsinferno.com,

Warning - Health Canada warns consumers not to use Nasutra due to ...  May 3, 2006
Health Canada is warning consumers not to use the product Nasutra because it has been found to contain the undeclared ingredient sildenafil (chemical name for ... - CNW Telbec (Communiqués de presse),

Fake Viagra maker given 10-year prison term  May 9, 2006
Some of the fake pills were found to contain medical starch, which does not have any curative effect and others had too much sildenafil, the main ingredient of ... - Xinhua,

Long Term Use Of Oral PDE-5 Inhibitors May Treat And Prevent ...  Apr 18, 2006
They studied a total of 4 men (3 with Sickle Cell disease and 1 Idiopathic) with frequent episodes of priapism and administered either sildenafil citrate (25 ... - UroToday,

Optic Neuropathy Patients Should Avoid Erectile Dysfunction Drugs  May 1, 2006
...de Presse Medicale for Reuters Health) - The Committee for Medicinal Products for Human Use (CHMP) said on Friday that Viagra (sildenafil), Cialis (tadalafil ... - UroToday,

Vitamin V(iagra) – ultimate sexual power booster  May 12, 2006
...partner? Your answer is Viagra (sildenafil citrate), also termed as Vitamin V by those who have experienced it and now vouch for it. ... - LiveArticles.org,

The Medical Company Offers Ability to Buy Cheap Viagra, Cheap ...  Apr 23, 2006
...online. Cheap Viagra or Cheap Cialis which contains Sildenafil Citrate enables many men with ED to respond to sexual stimulation. ... - PR Web (press release),

Potential new usage for Viagra  May 1, 2006
...“Although not very effective for angina, sildenafil [Viagra] has subsequently been shown to improve endothelial function in blood vessels in conditions such ... - Trade Arabia,

Generic Viagra suiting a common man’s purse  Apr 26, 2006
Ever since the discovery of the magical sildenafil citrate, Viagra has been ruling the market share and solving sexual dysfunction for millions of men facing ... - LiveArticles.org,

Spark your sexual life with Viagra  May 4, 2006
Exactly speaking; Viagra, an oral therapy for ED, is the citrate salt of sildenafil, which is a selective inhibitor of cyclic quanosine monophosphate-specific ... - LiveArticles.org,

CoTherix Reports First Quarter Results  May 3, 2006
Initiated Phase III trial of Ventavis in combination with sildenafil citrate to evaluate the safety and efficacy of the products in combination. ... - Yahoo! News (press release)

Drugs seized in horse racing probe  Apr 24, 2006
...home in Toronto and a steel company in Mississauga, authorities seized quantities of the blood builder Aranesp, bronchiol dilators and sildenafil citrate (more ... - SLAM! Sports,

Horse dopers busted  Apr 25, 2006
Also seized in the raid were bronchiole dilators and sildenafil citrate (generic Viagra), both believed to illegally enhance a horse's performance. ... - Ottawa Sun,

Warning On Medicines  Apr 26, 2006
Palace 'Capsules" by Unifier Sdn Bhd in Malaysia that are traditionally used to improve health were found to contain Acetildenafil, Sildenafil analog, which is ... - Bru Direct,

Ensure Quality Sexual Health with Viagra  Apr 19, 2006
Viagra contains sildenafil citrate, a very powerful drug responsible for inhibiting a crucial enzyme called PDE-5 (Phosphodiasterase-5). This enzyme degrades a ... - LiveArticles.org,

Men’s Health – Don’t ignore it  Apr 27, 2006
Sildenafil Citrate, whose brand name is Viagra, brought to the market by Pfizer and approved by FDA, is the most suitable oral treatment of male erectile ... - LiveArticles.org,

ORC Raids Drug Supplier  Apr 20, 2006
...used for performance enhancement were seized, including the blood builder Aranesp, strong analgesics, bronchiole dilators and sildenafil citrate (generic ... - Standardbred Canada,

Cialis Is Effective In The Treatment Of Men With Erectile ...  Apr 25, 2006
Viagra‚ (sildenafil citrate) was the first of the class to be introduced in 1998 and later followed by Levitra‚ (Vardenafil) and Cialis‚ (Tadalafil) in ... - Medical News Today (press release),

Love’sa step ahead of MS  Apr 24, 2006
...women. For men who cannot get or maintain an erection, there are oral medications such as sildenafil and vardenafil. Injectable ... - New Straits Times,

Effects of Other Drugs on Sildenafil Citrate

In Vitro Studies: Sildenafil metabolism is principally mediated by the cytochrome P450 (CYP) isoforms 3A4 (major route) and 2C9 (minor route). Therefore, inhibitors of these isoenzymes may reduce sildenafil clearance.

In Vivo Studies: Cimetidine (800 mg), a nonspecific CYP inhibitor, caused a 56% increase in plasma sildenafil concentrations when coadministered with sildenafil citrate (50 mg) to healthy volunteers.

When a single 100 mg dose of sildenafil citrate was administered with erythromycin, a specific CYP3A4 inhibitor, at steady state (500 mg bid for 5 days), there was a 182% increase in sildenafil systemic exposure (AUC). In addition, coadministration of the HIV protease inhibitor saquinavir, also a CYP3A4 inhibitor, at steady state (1200 mg tid) with sildenafil citrate (100 mg single dose) resulted in a 140% increase in sildenafil C_max and a 210% increase in sildenafil AUC. Sildenafil citrate had no effect on saquinavir pharmacokinetics. Stronger CYP3A4 inhibitors such as ketoconazole or itraconazole would be expected to have still greater effects, and population data from patients in clinical trials did indicate a reduction in sildenafil clearance when it was coadministered with CYP3A4 inhibitors (such as ketoconazole, erythromycin, or cimetidine).

Coadministration with the HIV protease inhibitor ritonavir, which is a highly potent P450 inhibitor, at steady state (400 mg bid) with sildenafil citrate (100 mg single dose) resulted in a 300% (4-fold) increase in sildenafil C_max and a 1000% (11-fold) increase in sildenafil plasma AUC. At 24 hours the plasma levels of sildenafil were still approximately 200 ng/mL, compared to approximately 5 ng/mL when sildenafil was dosed alone. This is consistent with ritonavir's marked effects on a broad range of P450 substrates. Sildenafil citrate had no effect on ritonavir pharmacokinetics.

It can be expected that concomitant administration of CYP3A4 inducers, such as rifampin, will decrease plasma levels of sildenafil.

Single doses of antacid (magnesium hydroxide/aluminum hydroxide) did not affect the bioavailability of sildenafil citrate.

Pharmacokinetic data from patients in clinical trials showed no effect on sildenafil pharmacokinetics of CYP2C9 inhibitors (such as tolbutamide, warfarin), CYP2D6 inhibitors (such as selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and related diuretics, ACE inhibitors, and calcium channel blockers. The AUC of the active metabolite, N-desmethyl sildenafil, was increased 62% by loop and potassium-sparing diuretics and 102% by nonspecific beta-blockers. These effects on the metabolite are not expected to be of clinical consequence.

Effects of Sildenafil Citrate on Other Drugs

In Vitro Studies: Sildenafil is a weak inhibitor of the cytochrome P450 isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 >150 mM). Given sildenafil peak plasma concentrations of approximately 1 mcM after recommended doses, it is unlikely that sildenafil citrate will alter the clearance of substrates of these isoenzymes.

In Vivo Studies: When sildenafil citrate 100 mg oral was coadministered with amlodipine, 5 mg or 10 mg oral, to hypertensive patients, the mean additional reduction on supine blood pressure was 8 mmHg systolic and 7 mmHg diastolic.

No significant interactions were shown with tolbutamide (250 mg) or warfarin (40 mg), both of which are metabolized by CYP2C9.

Sildenafil citrate (50 mg) did not potentiate the increase in bleeding time caused by aspirin (150 mg).

Sildenafil citrate (50 mg) did not potentiate the hypotensive effect of alcohol in healthy volunteers with mean maximum blood alcohol levels of 0.08%.

Sildenafil (100 mg) did not affect the steady state pharmacokinetics of the HIV protease inhibitors, saquinavir and ritonavir, both of which are CYP3A4 substrates.