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Erectile Dysfunction And Drug Interactions: My Canadian Pharmacy Technicians Warn Against

In one person in ten, at most, ED drugs can cause headaches, facial redness, stomach burns, myalgia and back pain. However, these are completely innocuous medicines. In one case, they can be dangerous if administered without medical supervision: if the patient is cardiopathic and takes nitrates. The combination of these treatments can cause a drop in blood pressure, up to collapse. Nitrates are contained in heart disease treatments such as nitroglycerin and drugs used in the treatment of angina pectoris. Sildenafil is also contraindicated for retinitis pigmentosa patients. In this article, we will give the floor to My Canadian Pharmacy technicians who explain the nature of PDE5 inhibitors and drug combinations that they should not become part of, whatever you do.


Viagra, Cialis, Levitra: best ED drugs of choice for My Canadian Pharmacy

Sildenafil was discovered during clinical trials carried out in the development of a drug to treat angina pectoris. From this molecule were born the two follow-ups, tadalafil and vardenafil. All three drugs work by imitating the natural body reaction: they are not aphrodisiac and help man reach erection only in the presence of a sexual stimulus. The efficacy of sildenafil starts about 30-40 minutes after intake and lasts up to 10 hours. There are three tablets on the market with different dosages, 25 mg, 50 mg and 100 mg. The positive effects of this treatment were found in 78% of patients with ED.

Vardenafil is a pill with doses of 5, 10 and 20 mg. Usually you take at least 30 minutes before having a sexual relationship and its effect may last as per sildenafil up to a maximum of 10 hours. 80% of patients demonstrated improvements in erectile capacity after taking this drug. Tadalafil is a pill of yellow color and has the shape of an almond. On the market there are 10 or 20 mg tablets. It should be taken between half an hour and an hour before sexual intercourse and the duration of its effects is 36 hours. This means for the patient the possibility of greater freedom of action. No need for any programming, it does not create any performance anxiety. Of this molecule there is also a reduced dose of 5 mg, to be taken daily, as a cure for impotence, eliminating the need to plan sexual intercourse.

Main drug interactions

‘Poppers’: The term “popper” is meant to indicate a set of particular chemicals, which are used for recreational purposes. More in detail, these substances belong to the class of alkyl nitrite (or alkyl nitrite – The latter, from a chemical point of view, are nothing but aliphatic, cyclic or heterocyclic esters of nitrous acid. Generally, when talking about popper, we refer to amylitrile nitrite products, isopropyl nitrite, butyl nitrite or isobutyl nitrite, but sometimes other compounds such as, for example, cyclohexyl nitrite. However, in most cases, when talking about popper, a mixture containing amyl nitrate and butyl nitrate is to be indicated. Alkyl nitrites are liquid compounds, generally yellow and highly flammable; Moreover, they are all characterized by high volatility.

It is no coincidence that the route of administration through which these substances are absorbed is just that of the inhaled type. The popper, in fact, are commonly “sniffed” directly from the glass bottle inside which they are contained. The smell of popper is quite characteristic and is often referred to as sweet and nauseating, or as pungent but still pleasing. In fact, some of these substances were also sold in the form of liquid incenses or home perfumes (in particular, butyl nitrite).

Macrolide antibiotics: Macrolides are a class of antibiotics of natural origin. The parent of this class is erythromycin, obtained from cultures of Streptomyces erythraeus. Macrolides – or macrolide antibiotics – have their name for the large nickel ring (from a chemical point of view, is a cyclic ester) that characterizes their chemical structure. Generally, this tetronic ring is made up of 14, 15 or 16 terms and binds two or more sugars. Macrolides constitute the prescription drugs for treating certain types of infection in patients who have had allergic reactions to penicillins because they have a similar spectrum of action. Macrolids possess bacteriostatic activity (ie they inhibit bacterial growth), but at high concentrations they can also become bactericidal (ie they are capable of killing bacterial cells).

Among the drugs belonging to this class of antibiotics, we mention erythromycin, clarithromycin, azithromycin and spiramycin. As mentioned above, macrolides possess a spectrum of action that may be comparable to that of mid-spectrum penicillins.

Macrolides are primarily administered orally, sometimes in the form of gastroresistant pharmaceutical formulations, since they are unstable in the stomach acid environment. They are used primarily for the treatment of non-serious systemic infections of the respiratory system, the mammary glands, the liver, the kidneys and the prostate.

More specifically, macrolides can be used to treat:

  • Infections of high and low respiratory tracts and soft tissues caused by Gram-positive bacteria such as Streptococcus pyogenes and Streptococcus pneumoniae;
  • Upper and lower respiratory tract infections and middle ear otitis caused by Haemophilus influenzae (usually in combination with a sulphamide);
  • Pneumonia for mycoplasmas;
  • Mycobacterium avium complex (MAC) infections in AIDS patients (usually rifabutin, an antibiotic belonging to the rifamycin class);
  • Morale of the Legionnaire;
  • Prophylaxis of bacterial endocarditis caused by Streptococcus viridans;
  • Gonorrhea;
  • Pelvic Inflammatory Disease (PID) caused by mixed infections by bactericidal cell wall bodies such as Chlamydia trachomatis.
  • In addition, clarithromycin may be used in a mixture of drugs used to treat gastric ulcer caused by Helicobacter pylori infections.

Macrolides exemplify their antibiotic action by interfering with the protein synthesis of bacteria. The synthesis of proteins in bacterial cells is due to specific organelles called ribosomes.

Ribosomes consist of ribosomal RNA (rRNA) and proteins, which are associated with two subunits:

  • 30S subunit, consisting of 21 proteins and one RNA molecule (16S);
  • 50S subunit, consisting of 34 proteins and two RNA molecules (23S and 5S).

The task of these organs is to bind and translate the messenger RNA (mRNA) from the cell nucleus and to synthesize the proteins for which it encodes. The macrolides are able to bind to the ribosomal subunit 50S. Specifically, these antibiotics bind in two well-specific regions to the 23S ribosomal RNA molecule. The macrolide-RNA binding 23S prevents the same RNA from completing protein synthesis, thus inhibiting bacterial growth.

Protease inhibitors. The HIV virus is responsible for the acquired human immunodeficiency virus (better known as AIDS). HIV is a Retrovirus, a particular type of RNA virus (learn more). To be able to replicate, this virus needs to convert its RNA into DNA; such conversion occurs thanks to a particular enzyme, reverse transcriptase. Some anti-HIV agents act by inhibiting, precisely, reverse transcriptase. Among these inhibitors, we mention zidovudine, didanosine, zalcitabine, lamivudine and stavudine. Other antiretroviral agents act by inhibiting HIV protease, a key enzyme for viral growth.

Ritonavir and indinavir are protease inhibitors. Protease inhibitors can be administered in combination with reverse transcriptase inhibitors to try to improve the effectiveness of the therapy. Consult your doctor who prescribes your protease inhibitor before taking Viagra.

Drugs that can mess with your erectile function

Many medicines may have an impact on the erectile function of man.

This is the case for the following medicines:

  • Antidepressants
  • Antihypertensive drugs
  • Lipid-lowering agents
  • Anti-epileptics
  • Anti-ulcer drugs
  • Antiarrhythmics, digitalis
  • Antiandrogens
  • Neuroleptics also often cause sexual problems.
  • Alphablockers; finasteride
  • Antiretroviral drugs prescribed for the AIDS virus
  • Cancer chemotherapy

However, it is important to remember that these medicines are prescribed for particular medical conditions. Before stopping any treatment, it is essential to seek the advice of your attending physician.



Many antidepressants do not have side effects that have an impact on libido and especially on erection in men. This is particularly the case of selective serotonin reuptake inhibitors. These drugs increase the level of serotonin, a neurotransmitter present in the brain. In men treated with these molecules for depression or anxiety, the best being begotten will have a direct impact: the return of desire. But it is not uncommon that because of this treatment, the erection is insufficient or difficult to obtain. The risk is that the patient prematurely ceases treatment, resulting in a return of depression.

This is why you should not hesitate to talk to your doctor about these side effects, even if they seem difficult to tackle. Other molecules can be proposed, without affecting the erection, but especially allowing the patient to cure his depressive episode.

My Canadian Pharmacy recommends for read: Depression in Men: Choosing the Right Treatment

Medications for high blood pressure

Hypertension, poorly known, especially in the oldest subjects, is a risk factor for infarction, stroke but also erectile dysfunction. The antihypertensive drugs most likely to cause erectile dysfunction are diuretics, beta-blockers and ACE inhibitors. There are, however, other types of antihypertensive agents that do not cause such side effects. Again, in the event of undesirable side effects on sexuality, it should be discussed with the doctor before suspending or stopping treatment.

Medications for cholesterol and diabetes

Statins, treatments used to treat excess cholesterol, are also likely to cause erectile dysfunction. Indeed, these drugs fight effectively against cholesterol but also lead to a decline in testosterone levels. However, this hormone plays an important role in the occurrence of an erection. Nevertheless the excess cholesterol altering the arteries, it can also be responsible for an erectile dysfunction. So do not hesitate to discuss this with your doctor who will prescribe a better treatment if needed.


Medications used to treat epilepsy (diphenylhydantoin, phenobarbital, carbamazepine, valproic acid, etc.) often have troublesome side effects. In particular, they decrease excitation and thus cause erectile dysfunction in humans. Stopping medication because of these troublesome side effects may seem like a good solution, but this will lead to an upsurge in the onset of seizures and may even prove dangerous.

Safety of Viagra intake reinforced by My Canadian Pharmacy

Before starting taking sildenafil, it is recommended that you consult your physician, especially in the presence of cardiovascular disease or other pathologies; in some risk subjects you may need to perform some medical examinations to avoid any possible complications.

The recommended starting dose of sildenafil for the treatment of erectile dysfunction in adults is 50 mg of medication to be taken as needed: the dose should be administered approximately 1 hour before the onset of the sexual act.

Dosage information and how to take Viagra – read in this guide:

It is recommended not to exceed the amount of a single dose per day. The recommended maintenance dose should be decided based on individual patient response and may vary from 25 to 100 mg, to be taken from 30 minutes to 4 hours before sexual intercourse. It is recommended not to exceed the amount of a daily dose. Use in the treatment of erectile dysfunction in the elderly The recommended dose of sildenafil for the treatment of erectile dysfunction in elderly or geriatric patients is 25 mg / day, to be taken approximately one hour before sexual activity.

Use of sildenafil in patients with liver or kidney problems. The dose recommended for the treatment of erectile dysfunction in patients with impaired renal or hepatic function should not exceed 25 mg of sildenafil per day, to be taken up to one hour before sexual activity. For the treatment of arterial pulmonary hypertension, however, there is no need to adjust the dose of sildenafil to be given.

Important considerations

Before starting treatment with erectile dysfunction with sildenafil you should always keep in mind that the medication does not work in the absence of sexual stimuli; in practice, sildenafil cannot help the patient have an erection if the latter does not have sufficient sexual stimulation.

Sildenafil is also a hypotensive drug, which, when administered with other drugs of similar properties – such as nitrates – may cause an excessive drop in blood pressure; Therefore, antihypertensive patients are advised to pay particular attention to taking sildenafil or to find another remedy for the treatment of erectile dysfunction.

The increase in sildenafil dose beyond the therapeutic doses does not in any way increase the effectiveness or the positive effect on erection. In fact, clinical studies have confirmed that the administration of sildenafil at 200 mg doses only increases the side effects of the drug without causing any variation in effectiveness; The same reasoning applies to doses even higher than sildenafil (single doses up to 800 mg of sildenafil were administered in the study).

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