IVF & Reproductive Medicine
One Molecule. Two Clinical Applications. SINDRELA — Sildenafil Citrate 25mg in Effervescent Form — Is Prescribed for Both Men and Women.
Sildenafil Citrate is known globally as a PDE5 inhibitor used for erectile dysfunction in men. What is far less well known — but increasingly important in reproductive medicine — is its application in women: improving uterine blood flow, supporting endometrial thickness and enhancing the conditions for successful embryo implantation in IVF protocols. SINDRELA from Quinek Life Sciences delivers 25mg of Sildenafil Citrate in an effervescent formulation — for faster onset, better tolerability and flexible clinical use across both indications.
What Is Sildenafil Citrate — and Why Is It Relevant to Both Men and Women?
Sildenafil Citrate belongs to the class of medicines known as Phosphodiesterase Type 5 (PDE5) inhibitors. Its mechanism is fundamentally about one thing: increasing blood flow through smooth muscle relaxation and vasodilation. In men, this effect on the vascular smooth muscle of the penile corpus cavernosum is what makes Sildenafil effective for erectile dysfunction. In women, the same mechanism — vasodilation and improved blood flow — is what makes it clinically useful for increasing uterine blood flow and supporting endometrial development.
The molecule does not discriminate between male and female physiology in its pharmacological action. PDE5 is expressed in smooth muscle tissue throughout the body — in penile arteries, uterine arteries, pulmonary arteries and elsewhere. Where there is PDE5 and where vasodilation would be clinically beneficial, Sildenafil has a potential role. This is why clinical research over the past two decades has increasingly explored its use in women undergoing IVF — particularly those with thin endometrium who have repeatedly failed embryo transfer despite good embryo quality.
SINDRELA’s 25mg dose is the lowest clinically recommended dose for both applications — appropriate as a starting point for men initiating erectile dysfunction treatment, and as the dose used in fertility protocols for women. The effervescent technology delivers this dose in a dissolving tablet format that provides faster dissolution, quicker onset and an alternative route of administration — dissolving in water and consumed as a solution — that may be better tolerated by patients who have difficulty swallowing conventional tablets.
“In a prospective self-controlled clinical trial, women given Sildenafil alongside Clomiphene achieved a mean endometrial thickness of 9.3mm compared to 6.6mm in cycles without Sildenafil (p<0.001). Uterine artery pulsatility index also dropped significantly — from 2.4 to 1.6 — indicating meaningfully improved uterine blood flow.”
— NCBI PMC5506766 — Sildenafil vaginal gel in women with prior Clomiphene failure due to thin endometrium
What Is Effervescent Technology — and Why Does It Matter for SINDRELA?
Effervescent technology (EVT) in pharmaceutical formulations refers to a tablet or granule that is designed to dissolve rapidly in water — releasing carbon dioxide through an acid-base reaction between citric acid and sodium bicarbonate components — creating an effervescent solution that is then consumed as a drink rather than swallowed as a solid tablet.
For Sildenafil Citrate, the effervescent formulation offers several pharmacokinetic and practical advantages. The drug is already in solution when ingested — meaning it does not need to dissolve in gastric fluid before it can be absorbed. This accelerates the onset of absorption compared to conventional tablet forms. The dissolved formulation also distributes more uniformly across the gastric mucosa, potentially improving consistency of absorption. And for patients — particularly older men with swallowing difficulties, or women who prefer not to take multiple solid tablets during fertility protocols — the effervescent format is often significantly more acceptable.
At 25mg, SINDRELA’s effervescent formulation provides the lowest recommended clinical dose in a fast-dissolving, easy-to-use format — suitable for both male and female clinical applications under physician prescription and supervision.
How Sildenafil Citrate Works — The PDE5 Inhibition Mechanism
The mechanism of Sildenafil Citrate begins with nitric oxide (NO) — a signalling molecule released by endothelial cells lining blood vessels in response to sexual stimulation (in men) or vascular stimulation (in both sexes). Nitric oxide activates an enzyme called Guanylate Cyclase, which produces cyclic Guanosine Monophosphate (cGMP). Cyclic GMP then causes smooth muscle cells in blood vessel walls to relax — triggering vasodilation and increased blood flow to the target tissue.
Phosphodiesterase Type 5 (PDE5) is the enzyme that breaks down cGMP — ending the vasodilation signal. Sildenafil selectively inhibits PDE5, preventing cGMP breakdown and allowing the vasodilatory effect to be sustained and amplified. The clinical outcome depends on which vascular bed is most relevant:
In Men
Penile Vascular Smooth Muscle
PDE5 inhibition in the corpus cavernosum of the penis allows cGMP to accumulate in response to sexual stimulation — sustaining smooth muscle relaxation, increasing penile arterial blood inflow and producing a physiological erection. Sildenafil does not cause erections in the absence of sexual stimulation — it amplifies the normal erectile response when stimulation is present. At 25mg — the lowest dose — SINDRELA provides an appropriate starting point for men initiating therapy for erectile dysfunction, particularly older patients, those on antihypertensive medications or those sensitive to hypotensive effects.
In Women (Fertility Protocols)
Uterine and Endometrial Vasculature
PDE5 is expressed in uterine artery smooth muscle. In women with poor uterine blood flow — a condition that produces a thin, poorly developed endometrial lining (less than 7mm) that is unable to support embryo implantation — Sildenafil’s vasodilatory action on uterine arteries increases uterine blood flow, improves endometrial perfusion and supports the growth of the endometrial lining to a thickness adequate for successful implantation. This use is off-label but is supported by a growing body of published clinical research and is increasingly incorporated into fertility protocols by reproductive medicine specialists across India.
Clinical Applications of SINDRELA — Men and Women
MALE
Erectile Dysfunction — Initiation and Sensitive Patients
Sildenafil Citrate 25mg is the recommended starting dose for men with erectile dysfunction who are older than 65, who take antihypertensive medicines, who have mild renal or hepatic impairment, or who are starting PDE5 inhibitor therapy for the first time and whose prescribing physician wants to assess tolerability before escalating to 50mg or 100mg. Erectile dysfunction affects a significant and growing proportion of Indian men — and SINDRELA’s effervescent format offers a practical, discreet and well-tolerated administration option. It should be taken 30–60 minutes before anticipated sexual activity. Sildenafil does not increase sexual desire — it supports the erectile mechanism when sexual stimulation is present.
FEMALE — IVF
Thin Endometrium in IVF / Frozen Embryo Transfer Cycles
A thin endometrial lining — generally defined as below 7mm on the day of trigger or transfer — significantly reduces the probability of successful embryo implantation in IVF and frozen embryo transfer (FET) cycles. In women who fail to achieve adequate endometrial thickness despite oestrogen supplementation, Sildenafil 25mg is used to improve uterine blood flow and support endometrial development. Published Indian clinical studies have confirmed significant improvements in endometrial thickness and uterine artery blood flow parameters with Sildenafil use in this setting. The Indian Journal of Health Sciences published a systematic review confirming that Sildenafil produced better outcomes than Estradiol Valerate in terms of uterine receptivity and endometrial vascularity in women undergoing IUI or IVF-ET.
FEMALE — IUI
IUI Protocols — Improving Endometrial Response to Stimulation
In IUI cycles where Clomiphene Citrate is used for ovulation induction, a well-recognised problem is that Clomiphene’s anti-oestrogenic effect on the endometrium can reduce endometrial thickness — sometimes to inadequate levels for implantation. Sildenafil 25mg administered during the follicular phase can counteract this anti-oestrogenic endometrial effect by improving uterine blood flow and supporting endometrial growth — offering a practical adjunct to Clomiphene-based IUI protocols when thin endometrium is a recurring problem.
FEMALE — RPL
Recurrent Pregnancy Loss With Poor Uterine Perfusion
In women with unexplained recurrent first-trimester pregnancy loss associated with high uterine artery resistance index (indicating poor uterine perfusion), Sildenafil has been studied as an adjunct to reduce uterine artery resistance and improve endometrial blood flow during the luteal phase. A published comparative study confirmed that Sildenafil produced more pronounced reductions in uterine artery pulsatility and resistance indices compared to Nifedipine — supporting its use in this setting under specialist reproductive medicine supervision.
Important Safety Information and Contraindications
Nitrate Contraindication — Absolute
SINDRELA is absolutely contraindicated in patients taking nitrate medicines in any form — including GTN (glyceryl trinitrate), isosorbide mononitrate or dinitrate, and amyl nitrite. The combination produces severe, potentially fatal hypotension. This contraindication applies to both male and female patients.
Cardiovascular Caution
Sildenafil causes a modest reduction in blood pressure. Caution is required in patients with pre-existing hypotension, dehydration, or significant left ventricular outflow obstruction. Use with alpha-blockers requires particular care — a low starting dose and adequate interval between doses is essential.
Vision and Hearing
Rare cases of non-arteritic anterior ischaemic optic neuropathy (NAION) and sudden hearing loss have been reported with PDE5 inhibitors. Patients should be advised to seek immediate medical attention if they experience sudden visual or hearing changes during or after Sildenafil use.
Female Use — Off-Label
Sildenafil’s use in women for fertility indications is an off-label application — supported by growing clinical evidence but not formally approved by CDSCO for female reproductive indications. All female prescriptions must be made by a qualified reproductive medicine specialist on the basis of clinical assessment. Informed consent regarding off-label use is recommended.
Why Effervescent Technology Matters for SINDRELA — Summary
Faster onset — Sildenafil is already dissolved when consumed, accelerating gastric absorption versus a conventional tablet that must first dissolve in gastric fluid. This is clinically meaningful for erectile dysfunction where timing relative to sexual activity matters.
Better tolerability — Effervescent formulations tend to be gentler on the gastric mucosa than conventional solid-dose forms. For patients who report gastric discomfort with standard Sildenafil tablets, the effervescent format may be better tolerated.
Administration flexibility — The dissolved format is an alternative for patients with dysphagia or those who prefer not to take solid tablets as part of a complex daily medication regimen during IVF protocols.
Quinek Life Sciences — IVF & Reproductive Medicine
SINDRELA — Sildenafil Citrate 25mg EVT, From a WHO-GMP Certified Reproductive Medicine Specialist
SINDRELA is part of Quinek Life Sciences’ IVF and reproductive medicine portfolio — formulated for fertility specialists and reproductive medicine physicians who need a reliable, well-tolerated Sildenafil Citrate 25mg option in effervescent form for both male and female clinical applications. Manufactured at our WHO-GMP, GLP and ISO certified facilities.
Quinek Life Sciences’ IVF segment covers the full pharmaceutical spectrum of assisted reproductive medicine — from ovarian stimulation and luteal support to endometrial preparation and male fertility. SINDRELA represents our commitment to offering formulations that address the less commonly served but clinically critical areas of reproductive medicine — including endometrial support for women and well-tolerated ED management for men.
One Molecule. Two Patient Populations. One Quality Standard.
Sildenafil Citrate’s clinical story has evolved significantly since its original development. From a cardiovascular medicine that surprised researchers with its erectile effects, to a well-established ED treatment, to an increasingly recognised tool in female fertility medicine — the range of clinical applications continues to expand as the understanding of PDE5’s role in vascular smooth muscle across the body deepens.
SINDRELA — Sildenafil Citrate 25mg in Effervescent Technology from Quinek Life Sciences — serves both the man whose quality of life is affected by erectile dysfunction and the woman whose IVF journey depends on adequate endometrial blood flow. Different patients. Different clinical needs. The same pharmacological mechanism. The same WHO-GMP quality standard in every tablet.
Medical Disclaimer: This article is for educational purposes and healthcare professional reference only. SINDRELA must be prescribed by a qualified physician. Female use in fertility protocols is an off-label application and must be undertaken under the supervision of a qualified reproductive medicine specialist with informed patient consent. Sildenafil is contraindicated with nitrate medicines.
Sources: NCBI PMC5506766 — Sildenafil in CC Failure With Thin Endometrium · Indian Journal of Health Sciences — Sildenafil and Female Infertility · NCBI PMC9335401 — Vaginal Sildenafil vs G-CSF for Endometrial Thickness · FACTS About Fertility — Sildenafil in Women With Thin Endometrium (Meta-Analysis, 1452 Patients) · FDA Prescribing Information — Sildenafil Citrate · Quinek Life Sciences IVF Segment
