The platform uses special capsules that contain between 50 and 150 colorants, from which a specific color or specific colors can be selected later in the drug development process. Lonza sees a substantial customer base for the product, and argues its new system allows clients to still meet regulatory guidelines while also proving flexibility to pharma companies and marketers. Some men in a recent study had persistent, blue-tinted vision after taking sildenafil, the active ingredient in Viagra. Many men take the erectile dysfunction drug sildenafil, the active ingredient in Viagra, without problems. But in rare cases, they may experience an odd side effect: changes in eyesight, including blue-tinted vision, that last for several weeks, according to a new report. The report, published Friday (Feb.
Rights and permissions
All of the men in the current report were first-time sildenafil users, and all of them took the highest recommended dose of the drug, 100 milligrams. What's more, none of the men had a prescription for the medication. It's unclear why some people are more prone than others to persistent side effects from sildenafil. But it may be that their bodies do not break down the drug very efficiently, which could lead to high concentrations of the medication in their blood, much higher than what's seen in average users, Karaarslan said. Because it's unclear who will experience such side effects, Karaarslan said men should start on lower doses of the drug.
Viagra and foods
Indeed, it's recommended that patients start with a 50-mg dose and increase or decrease the amount depending on their reaction, according to Pfizer, the maker of Viagra. What's more, patients should take the drug under medical supervision, meaning they sildenafil 5mg for sale should get a prescription for it, Karaarslan added. "Although these drugs, when used under the control of physicians and at the recommended doses, provide very important sexual and mental support, uncontrolled and inappropriate doses should not be used or repeated," said Karaarslan. 'Eye' can't look: 9 eyeball injuries that will make you squirm Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. 7) in the journal Frontiers in Neurology, describes the cases of 17 men who visited a hospital in Turkey with vision problems that persisted for more than 24 hours after they'd taken sildenafil. The problems reported included blurred vision, sensitivity to light, reduced eyesight and changes to color perception, including "intensely blue-colored vision," a side effect known as cyanopsia. Those with cyanopsia also reported "red-green colorblindness," in which red and green hues appear to be brownish, the report said. None of the patients had a history of eye disease or colorblindness. While it's known that sildenafil can cause temporary vision changes, including blurred vision and cyanopsia, these side effects typically disappear within 3 to 5 hours. Persistent vision changes, like those seen in this report, are much rarer. Fortunately, the vision problems for all of the men described in this report went away after 21 days. "For the vast majority of men, any side effects [of sildenafil] will be temporary and mild," study author Dr. Cüneyt Karaarslan, of the Dünyagöz Adana hospital in Turkey, said in a statement. "However, I wanted to highlight that persistent eye and vision problems may be encountered for a small number of users." Last year, researchers in Massachusetts reported the case of a man who developed vision loss, including "doughnut-shaped" spots in his vision, which lasted for at least two months after he'd consumed an entire bottle of liquid sildenafil. Related: Viagra goes generic: 5 interesting facts about the 'little blue pill' Get the world’s most fascinating discoveries delivered straight to your inbox. Sildenafil treats erectile dysfunction by inhibiting an enzyme called phosphodiesterase 5 (PDE5), which plays a role in regulating blood flow to the penis.
- The cost-effectiveness of generic sildenafil has increased its accessibility.
- It can cause flushing due to vasodilation, which is usually harmless.
- Taking it more than once a day is not recommended due to half-life.
- The medication is excreted primarily in the feces and to a lesser extent in urine.
- It is important to distinguish between sildenafil and other PDE5 inhibitors.
- The blue color helps patients and pharmacists identify the medication quickly.
- A doctor may recommend a trial dose to assess tolerance and response.
But sildenafil also inhibits a related enzyme called phosphodiesterase type 6 (PDE6), which is found in retinal cells, the light-sensitive cells at the back of the eye. It's thought that, in high doses, this inhibition leads to the buildup of a molecule that is toxic to retinal cells, Live Science previously reported. All of the men in the current report were first-time sildenafil users, and all of them took the highest recommended dose of the drug, 100 milligrams. What's more, none of the men had a prescription for the medication.
| Product | Dosage | Quantity + Bonus | Price | |
|---|---|---|---|---|
| Viagra Generic | 50mg | 270 + 8 Pills | 198.48€ 189.03€ | |
| Kamagra Polo | 100mg | 12 Pills | 60.21€ 57.34€ | |
| Viagra Generic | 100mg | 180 + 8 Pills | 199.37€ 189.88€ | |
| Viagra Generic | 200mg | 90 + 6 Pills | 170.79€ 162.66€ | |
| Kamagra | 100mg | 32 Pills | 121.24€ 115.47€ | |
| Viagra Generic | 200mg | 60 + 4 Pills | 125.19€ 119.23€ | |
| Kamagra | 100mg | 180 + 6 Pills | 436.79€ 415.99€ | |
| Viagra Generic | 50mg | 30 + 4 Pills | 54.26€ 51.68€ | |
| Viagra Generic | 100mg | 20 Pills | 45.58€ 43.41€ | |
| Kamagra | 100mg | 360 + 6 Pills | 839.95€ 799.95€ | |
| Kamagra Oral Jelly | 100mg | 110 + 9 Sachets | 334.87€ 318.92€ |
It's unclear why some people are more prone than others to persistent side effects from sildenafil. But it may be that their bodies do not break down the drug very efficiently, which could lead to high concentrations of the medication in their blood, much higher than what's seen in average users, Karaarslan said. Because it's unclear who will experience such side effects, Karaarslan said men should start on lower doses of the drug.
Adverse effects
“We were able to show that Viagra enhanced the lethality of breast cancer chemotherapy doxorubicin against prostate cancer cells[2] .” Dent’s group has also looked at combining PDE-5 inhibitors with the newer cancer-fighting kinase inhibitors. “We discovered that, for example, PDE-5 inhibitors can enhance the lethality of Bayer’s sorafenib (Nexavar) and regorafenib (Stivarga) in gastrointestinal tumours (including liver, pancreatic and bowel cancer)[3] .” “What we observed was that Viagra particularly — as that’s what we’ve tended to work with — was very good at enhancing the ability of these drugs to activate death receptor signalling. But it was also really good at inducing a toxic form of autophagy, so a couple of things were going on,” says Dent. Dent has also seen good results in the treatment of brain tumours. Getting cancer drugs into the brain is a problem, but PDE-5 inhibitors seem to help. Indeed, it's recommended that patients start with a 50-mg dose and increase or decrease the amount depending on their reaction, according to Pfizer, the maker of Viagra.
Why trust our experts?
A phase I trial at the Ottawa Hospital Research Institute in Canada is trialling tadalafil use for five days before abdominal cancer surgery until ten days after, in combination with a protective influenza vaccine, to see if this impacts on cancer reoccurrence. PDE-5 inhibitors have really proven to be excellent drugs for repurposing in anti-cancer therapeutics PDE-5 inhibitors also seem to have a role in enhancing patients’ responses to existing chemotherapy drugs. There are the obvious vasodilating effects that may allow more of a drug to reach its tumour targets but there is also evidence that tumour cells over-express PDE-5 in breast, liver and lung cancers, so there may be other mechanisms at play. Paul Dent’s laboratory at Virginia Commonwealth University in the United States is dedicated to developmental cancer therapeutics and is involved in several collaborations to investigate the impact of PDE-5 inhibitors and cancer drugs. “PDE-5 inhibitors have really proven to be excellent drugs for repurposing in anti-cancer therapeutics,” says Dent. What's more, patients should take the drug under medical supervision, meaning they sildenafil 5mg for sale should get a prescription for it, Karaarslan added. "Although these drugs, when used under the control of physicians and at the recommended doses, provide very important sexual and mental support, uncontrolled and inappropriate doses should not be used or repeated," said Karaarslan. 'Eye' can't look: 9 eyeball injuries that will make you squirm Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022.
- The generic name "sildenafil" is less known than the brand name "Viagra."
- It can cause jaw pain or toothache as an uncommon side effect.
- The medication should be stored at temperatures between 15-30°C (59-86°F).
- It is not approved for use in combination with other ED treatments.
- The blue film coat may contain polyethylene glycol or titanium dioxide.
- It is essential to report any allergic reactions, such as hives or swelling.
- Patients with penile implants or prostheses should not use sildenafil.
She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. in molecular biology and an M.S. in biology from the University of California, San Diego.
Repurposing problems
The platform uses special capsules that contain between 50 and 150 colorants, from which a specific color or specific colors can be selected later in the drug development process. Lonza sees a substantial customer base for the product, and argues its new system allows clients to still meet regulatory guidelines while also proving flexibility to pharma companies and marketers. Some men in a recent study had persistent, blue-tinted vision after taking sildenafil, the active ingredient in Viagra. Many men take the erectile dysfunction drug sildenafil, the active ingredient in Viagra, without problems. But in rare cases, they may experience an odd side effect: changes in eyesight, including blue-tinted vision, that last for several weeks, according to a new report.
Dosage is too low
The report, published Friday (Feb. 7) in the journal Frontiers in Neurology, describes the cases of 17 men who visited a hospital in Turkey with vision problems that persisted for more than 24 hours after they'd taken sildenafil. The problems reported included blurred vision, sensitivity to light, reduced eyesight and changes to color perception, including "intensely blue-colored vision," a side effect known as cyanopsia. Those with cyanopsia also reported "red-green colorblindness," in which red and green hues appear to be brownish, the report said. None of the patients had a history of eye disease or colorblindness. Her work has appeared in Scienceline, The Washington Post and Scientific American. The infamous ‘little blue pill’, Viagra (sildenafil), is one of the world’s most successful products of drug repurposing — widening a drug’s use for more than one indication. Originally developed in the 1990s by Pfizer to treat hypertension and angina, it became apparent during clinical trials that sildenafil induced penile erections, and the rest, as they say, is history. Now, basic scientific data and results from clinical studies have suggested that sildenafil and other phosphodiesterase type 5 (PDE-5) inhibitors, such as tadalafil, may have multiple applications in cancer, heart failure, neurodegenerative diseases, circulatory disorders and even infectious diseases. “In some ways, repurposing is a standard part of drug development,” says Pan Pantziarka from the Anticancer Fund, a research initiative based in Brussels.
MYTH #4: “Taking this pill is addictive”
in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American. The infamous ‘little blue pill’, Viagra (sildenafil), is one of the world’s most successful products of drug repurposing — widening a drug’s use for more than one indication. Originally developed in the 1990s by Pfizer to treat hypertension and angina, it became apparent during clinical trials that sildenafil induced penile erections, and the rest, as they say, is history.
What if Sildenafil isn’t working for me?
Now, basic scientific data and results from clinical studies have suggested that sildenafil and other phosphodiesterase type 5 (PDE-5) inhibitors, such as tadalafil, may have multiple applications in cancer, heart failure, neurodegenerative diseases, circulatory disorders and even infectious diseases. “In some ways, repurposing is a standard part of drug development,” says Pan Pantziarka from the Anticancer Fund, a research initiative based in Brussels. “Once [a pharmaceutical company] has a licence, they then seek to repurpose [the drug].” Pantziarka is programme director for drug repurposing and coordinator of the Repurposing Drugs in Oncology (ReDO) project ( an international collaboration between the Anticancer Fund and the not-for-profit drug development organisation GlobalCures, based in Massachusetts. According to the US government trials registry, there are over 650 trials for PDE-5 inhibitors ongoing for an array of conditions. But with first-generation PDE-5 inhibitors off-patent since 2013, and limited interest from the pharmaceutical industry, there is no clear path to repurposing. “Once [a pharmaceutical company] has a licence, they then seek to repurpose [the drug].” Pantziarka is programme director for drug repurposing and coordinator of the Repurposing Drugs in Oncology (ReDO) project ( an international collaboration between the Anticancer Fund and the not-for-profit drug development organisation GlobalCures, based in Massachusetts. According to the US government trials registry, there are over 650 trials for PDE-5 inhibitors ongoing for an array of conditions. But with first-generation PDE-5 inhibitors off-patent since 2013, and limited interest from the pharmaceutical industry, there is no clear path to repurposing. The challenges involved in running trials with off-patent drugs is partly why ReDo exists. “I became involved because my son had osteosarcoma, and he didn’t respond to standard treatments,” says Pantziarka. “I found that there were people who were looking at non-cancer drugs which had some evidence of activity in cancer.” Sadly, Pantziarka was not able to find a treatment for his son, who died in 2011, but he ended up moving from a job in computer science to oncology research and now focuses on commercially neglected therapeutic areas, including repurposing. You can bypass the early stages of trials, so in theory the path should be clear to rapid adoption, should we have positive results “Our intention is to find treatments we can get to patients quickly and repurposing really fits the bill very well,” he explains. “You can bypass the early stages of trials, so in theory the path should be clear to rapid adoption, should we have positive results.” As part of the ReDo project, Pantziarka has built up a database of around 270 drugs with some potential to be repurposed as cancer therapies and this includes PDE-5 inhibitors. “Drugs like the PDE-5 inhibitors actually have a tremendous amount of existing evidence. Not just in vitro studies, but supporting data from extensive animal models, human data, case reports, and small clinical trials.” Pantziarka explains that PDE-5 inhibitors have an immunological effect in cancer (see Figure). “There is quite a wide range of evidence to show that actually these drugs can take the brakes off the immune response, so they help the anti-tumour immune response get into gear,” he says.
- Can be used by men who have undergone prostate surgery, with doctor's approval.
- The pill should be taken on an as-needed basis, not scheduled daily.
- It is not addictive and does not lead to dependence with proper use.
- Some users report improved confidence and reduced performance anxiety.
- The medication is stable at room temperature, avoiding extreme heat or moisture.
- It is available in both brand and generic forms from licensed pharmacies.
- Patients with bleeding disorders or active peptic ulcers should use caution.
Figure 1: PDE-5 inhibitors and cancer One suggestion is to use PDE-5 inhibitors in cancer patients after surgery to try to reduce cancer reoccurrences[1] .
Is generic medication less effective than brand-name medication?
While it's known that sildenafil can cause temporary vision changes, including blurred vision and cyanopsia, these side effects typically disappear within 3 to 5 hours. Persistent vision changes, like those seen in this report, are much rarer. Fortunately, the vision problems for all of the men described in this report went away after 21 days. "For the vast majority of men, any side effects [of sildenafil] will be temporary and mild," study author Dr. Cüneyt Karaarslan, of the Dünyagöz Adana hospital in Turkey, said in a statement.
Is Viagra a blood thinner?
"However, I wanted to highlight that persistent eye and vision problems may be encountered for a small number of users." Last year, researchers in Massachusetts reported the case of a man who developed vision loss, including "doughnut-shaped" spots in his vision, which lasted for at least two months after he'd consumed an entire bottle of liquid sildenafil. Related: Viagra goes generic: 5 interesting facts about the 'little blue pill' Get the world’s most fascinating discoveries delivered straight to your inbox. Sildenafil treats erectile dysfunction by inhibiting an enzyme called phosphodiesterase 5 (PDE5), which plays a role in regulating blood flow to the penis. But sildenafil also inhibits a related enzyme called phosphodiesterase type 6 (PDE6), which is found in retinal cells, the light-sensitive cells at the back of the eye. It's thought that, in high doses, this inhibition leads to the buildup of a molecule that is toxic to retinal cells, Live Science previously reported. “Because the PDE-5 inhibitors work on an immunological basis, and we think that the post-surgical reoccurrence is partly immune based, that is a really good fit,” says Pantziarka. A phase I trial at the Ottawa Hospital Research Institute in Canada is trialling tadalafil use for five days before abdominal cancer surgery until ten days after, in combination with a protective influenza vaccine, to see if this impacts on cancer reoccurrence. PDE-5 inhibitors have really proven to be excellent drugs for repurposing in anti-cancer therapeutics PDE-5 inhibitors also seem to have a role in enhancing patients’ responses to existing chemotherapy drugs. There are the obvious vasodilating effects that may allow more of a drug to reach its tumour targets but there is also evidence that tumour cells over-express PDE-5 in breast, liver and lung cancers, so there may be other mechanisms at play. Paul Dent’s laboratory at Virginia Commonwealth University in the United States is dedicated to developmental cancer therapeutics and is involved in several collaborations to investigate the impact of PDE-5 inhibitors and cancer drugs.
| Form | Packaging Options | Storage Conditions |
|---|---|---|
| Tablets | Blister packs of 10, 20, 30 | Store below 25°C, dry place |
| Sublingual | Small blister packs | Keep away from moisture |
| Liquid solution | Bottles of 10 mL | Refrigerate if recommended |
“PDE-5 inhibitors have really proven to be excellent drugs for repurposing in anti-cancer therapeutics,” says Dent. “We were able to show that Viagra enhanced the lethality of breast cancer chemotherapy doxorubicin against prostate cancer cells[2] .” Dent’s group has also looked at combining PDE-5 inhibitors with the newer cancer-fighting kinase inhibitors. “We discovered that, for example, PDE-5 inhibitors can enhance the lethality of Bayer’s sorafenib (Nexavar) and regorafenib (Stivarga) in gastrointestinal tumours (including liver, pancreatic and bowel cancer)[3] .” “What we observed was that Viagra particularly — as that’s what we’ve tended to work with — was very good at enhancing the ability of these drugs to activate death receptor signalling. But it was also really good at inducing a toxic form of autophagy, so a couple of things were going on,” says Dent. Dent has also seen good results in the treatment of brain tumours. Getting cancer drugs into the brain is a problem, but PDE-5 inhibitors seem to help.
How does Viagra work to treat ED?
The challenges involved in running trials with off-patent drugs is partly why ReDo exists. “I became involved because my son had osteosarcoma, and he didn’t respond to standard treatments,” says Pantziarka. “I found that there were people who were looking at non-cancer drugs which had some evidence of activity in cancer.” Sadly, Pantziarka was not able to find a treatment for his son, who died in 2011, but he ended up moving from a job in computer science to oncology research and now focuses on commercially neglected therapeutic areas, including repurposing. You can bypass the early stages of trials, so in theory the path should be clear to rapid adoption, should we have positive results “Our intention is to find treatments we can get to patients quickly and repurposing really fits the bill very well,” he explains. “You can bypass the early stages of trials, so in theory the path should be clear to rapid adoption, should we have positive results.” As part of the ReDo project, Pantziarka has built up a database of around 270 drugs with some potential to be repurposed as cancer therapies and this includes PDE-5 inhibitors.
How it works for PAH
“Drugs like the PDE-5 inhibitors actually have a tremendous amount of existing evidence. Not just in vitro studies, but supporting data from extensive animal models, human data, case reports, and small clinical trials.” Pantziarka explains that PDE-5 inhibitors have an immunological effect in cancer (see Figure). “There is quite a wide range of evidence to show that actually these drugs can take the brakes off the immune response, so they help the anti-tumour immune response get into gear,” he says. Figure 1: PDE-5 inhibitors and cancer One suggestion is to use PDE-5 inhibitors in cancer patients after surgery to try to reduce cancer reoccurrences[1] . “Because the PDE-5 inhibitors work on an immunological basis, and we think that the post-surgical reoccurrence is partly immune based, that is a really good fit,” says Pantziarka.