Cock Bombs Explained: Sildenafil and Tadalafil in One Tablet

Cock Bombs is a combination tablet. Each one holds 50 mg of sildenafil and 20 mg of tadalafil, which is where the 70 mg on the label comes from. Those are the two best known PDE5 inhibitors, sold on their own as Viagra and Cialis.

Putting both in one tablet is not something you find in approved medicine, so it is worth being clear about what each ingredient does, why anyone would pair them, and what stacking two drugs on the same enzyme actually means.

What is in the tablet

• Sildenafil at 50 mg, approved in 1998 as Viagra, which is a standard tablet strength on its own.
• Tadalafil at 20 mg, approved in 2003 as Cialis, which is also a standard single tablet strength.

Both ingredients are real, well characterized drugs with decades of clinical data behind them individually. Sildenafil is also approved separately for pulmonary arterial hypertension, and tadalafil is approved for benign prostatic hyperplasia as well. What has no approval anywhere is the combination, and no regulator has assessed the two together in one tablet.

The single ingredient versions are stocked separately as sildenafil and tadalafil.

How PDE5 inhibitors work

The mechanism is worth following, because it explains both the effects and the warnings. Sexual arousal causes nerve endings and the lining of blood vessels in the penis to release nitric oxide. That triggers an enzyme called guanylate cyclase to produce cGMP, a messenger molecule. cGMP tells the smooth muscle in the artery walls and in the erectile tissue to relax, which lets blood flow in and produces an erection.

An enzyme called phosphodiesterase type 5, or PDE5, breaks cGMP down again. That is the off switch. Sildenafil and tadalafil block PDE5, so cGMP stays around longer and the relaxation lasts.

The important consequence is that these drugs do not create arousal. They stop a signal from being cleared away, and if arousal never produced the nitric oxide in the first place there is no signal to preserve. This is the sharpest difference from PT-141, which acts on melanocortin receptors in the brain rather than on blood vessels, and works on desire rather than on plumbing.

PDE5 also sits in blood vessel walls elsewhere in the body, which is why blood pressure effects, flushing and nasal congestion turn up as side effects, and why the nitrate warning below exists.

Why the two behave differently

They hit the same enzyme, but their pharmacokinetics are not alike, and that is the entire rationale for combining them.

Sildenafil

Half-life around 4 hours, with a working window of roughly 4 to 6 hours. It comes on relatively quickly, usually within 30 to 60 minutes, and a heavy or fatty meal slows absorption noticeably.

Sildenafil is selective for PDE5 but has measurable activity at PDE6, which is found only in the retina and is part of visual transduction. That cross-reactivity is why a minority of users report a blue tinge to their vision or increased light sensitivity. The effect is temporary and tracks the drug leaving the system.

Tadalafil

Half-life around 17.5 hours, which gives it a duration of up to 36 hours and the nickname it picked up years ago. Food has little effect on it, so timing around meals is less of a consideration.

Tadalafil is highly selective for PDE5 and has almost no PDE6 activity, so the visual effects are rare with it. It does inhibit PDE11, an enzyme found in heart, pituitary and testicular tissue whose function is still not well described. The back pain and muscle aching that some people get with tadalafil and not with sildenafil is generally attributed to that.

Why anyone combines them

The stated logic is straightforward: sildenafil comes on fast, tadalafil lasts a long time, so a tablet holding both is meant to give you the front end of one and the tail of the other.

That reasoning is coherent on paper. It is also worth measuring against the principle that applies to combining anything, which we set out in the downsides of peptides: two compounds acting on the same target usually add side effects faster than they add effect. Sildenafil and tadalafil both inhibit PDE5. This is not two drugs covering different steps of a process, it is two drugs doing the same job with different timing.

Because the blood pressure effect comes from the same enzyme blockade, the fall in blood pressure from two PDE5 inhibitors is additive in a way that the convenience is not. No clinical trial has tested this pairing, so there is no published data on where that lands. Read the pharmacology on both ingredients and decide for yourself what that trade looks like.

The nitrate warning

This one is not a general caution, it is an absolute contraindication on the label of every PDE5 inhibitor ever approved, and the reason is mechanical.

Nitrate medicines work by donating nitric oxide, the same molecule at the top of the pathway described above. A PDE5 inhibitor blocks the breakdown at the bottom of that pathway. Push more signal in at one end while blocking its removal at the other and cGMP accumulates throughout the circulation, which can drop blood pressure to a level that is life threatening.

Nitrates include nitroglycerin in all its forms, isosorbide mononitrate and dinitrate, and amyl nitrite, which is sold recreationally as poppers. Riociguat, used for pulmonary hypertension, is contraindicated for the same reason through a different step. Tadalafil’s long half-life makes this window wider than people assume, since it is still present well over a day later.

Alpha blockers prescribed for blood pressure or prostate symptoms also lower blood pressure and are a documented interaction rather than a contraindication.

Side effects and the rare ones worth knowing

The common effects are shared across the class and follow from PDE5 sitting in blood vessels body-wide: headache, facial flushing, nasal congestion, indigestion and dizziness. Sildenafil adds the visual tinge, tadalafil adds back and muscle ache.

Three uncommon events appear in the labeling and are worth recognizing.

• Priapism, meaning an erection lasting more than four hours, is a medical emergency, because trapped blood loses oxygen and tissue damage becomes permanent. It needs an emergency room rather than a wait.
• Sudden vision loss has been reported as non-arteritic anterior ischemic optic neuropathy, where blood flow to the optic nerve is interrupted. It is rare, and turns up more often in people with existing risk factors.
• Sudden hearing loss is also rare, and sometimes arrives with tinnitus or dizziness alongside it.

Anyone with cardiovascular disease is in a different position with this class generally, because sexual activity is itself a cardiac load and these drugs lower blood pressure on top of it.

How the body clears them

Both are small molecules processed in the liver by CYP3A4, which is the busiest drug metabolizing enzyme there is. That matters in two directions.

Anything that inhibits CYP3A4 slows their clearance and raises blood levels. Ketoconazole, ritonavir, clarithromycin and grapefruit juice all belong in that group. Anything that induces the enzyme, such as rifampicin or St John’s wort, does the reverse.

This is a useful contrast with most of the rest of the catalog. Peptides are broken apart by peptidases and cleared largely through the kidneys rather than run through liver P450 enzymes, which is why they carry far fewer interactions of this kind. We go through that difference in peptides and the liver. Sildenafil and tadalafil are not peptides, and they behave like the small molecules they are.

Alcohol is worth a line of its own. It lowers blood pressure, it works against erectile function directly, and it adds to the dizziness these drugs already cause.

Handling and storage

Tablets are much easier to store than the freeze dried material most of this catalog is made of. Keep them cool, dry, sealed and out of direct light, and no reconstitution or refrigeration is involved. Nothing in the reconstitution guide applies here.

The one storage point specific to combination tablets is identification. A tablet holding two actives looks like any other tablet, so keeping it in its labeled container matters more than usual, particularly given the nitrate interaction.

Common questions

Is sildenafil the same thing as Viagra?

Sildenafil is the drug, Viagra is Pfizer’s brand name for it. Tadalafil and Cialis have the same relationship. The patents expired years ago, which is why the generic names are now the common ones.

Are these peptides?

Neither one is. Both are synthetic small molecules that inhibit an enzyme rather than amino acid chains that bind a receptor. PT-141 is the peptide in this category, and it works through an entirely different route. The distinction is covered in what peptides actually do.

Why is tadalafil called the weekend pill?

Its 17.5 hour half-life gives it a window of up to 36 hours, so a dose taken on a Friday is still active well into the weekend. Sildenafil’s 4 hour half-life gives it nothing comparable.

Does food matter?

For sildenafil yes, a fatty meal slows absorption and delays onset. For tadalafil it makes little difference. In a tablet containing both, the sildenafil half is the part affected.

What does the 70 mg on the label mean?

It is the two actives added together, 50 mg of sildenafil plus 20 mg of tadalafil. It is not 70 mg of any single ingredient, which is worth being clear about since the two are not interchangeable.

TL;DR

Cock Bombs pairs 50 mg of sildenafil with 20 mg of tadalafil, adding up to the 70 mg on the label. Both block PDE5, the enzyme that clears the cGMP signal driving smooth muscle relaxation, so neither creates arousal and both depend on it. Sildenafil has a 4 hour half-life, comes on fast, is slowed by fatty food and touches PDE6 in the retina. Tadalafil has a 17.5 hour half-life, runs up to 36 hours, ignores food and touches PDE11. Combining them targets the same enzyme twice, so blood pressure effects are additive and no trial has tested the pairing. Nitrates in any form, including poppers, are an absolute contraindication, and both drugs are cleared by liver CYP3A4, which is where their interactions come from.

Everything we supply is lab tested for purity and identity, and sold as research grade material for laboratory and research use. Read the pharmacology on both ingredients and decide for yourself what it supports. See the product page or browse the sexual health range.

Featured image from Rawpixel, public domain.