英文药名：sildeHEXL Tabletten

中文药名：西地那非片

生产厂家：Hexal
药品介绍
【使用说明】
一般在性生活前30分钟至1小时服用，年纪较大的患者，由于药物吸收慢，需提前1小时服用。服用万艾可(伟哥)后，还需要在一定的性刺激下才能发挥作用。性刺激有视听觉刺激、接吻、抚摸等。老年夫妇因性刺激力度不够，亦影响万艾可(伟哥)疗效。
【用法用量】
对大多数患者，推荐初始剂量为50MG，在性活动前约1小时服用；但在性活动前0.5～ 4小时内的任何时候服用均可。基于药效和耐受性，剂量可增加至100毫克（最大推荐剂量）或降低至25毫克。每日最多服用1次。
下列因素与血浆西地那非水平（AUC）增加有关：年龄65岁以上（增加40%）、肝脏受损（如肝硬化，增加80%）、重度肾损害（肌酐清除率﹤30ml/分，增加100%）、同时服用强效细胞色素P450 3A4抑制剂（酮康唑、伊曲康唑增加200%）、红霉素增加 182%、saquinavir增加210%。由于血浆水平较高可能同时增加药效和不良事件发生率，故这些患者的起始剂量以25MG为宜。
研究表明，HIV蛋白酶抑制剂Ritonavir可使西地那非血药水平显著增高（AUC增加了11倍）。有鉴于此，建议服用Ritonavir的患者，每48小时内用药剂量最多不超过 25MG。
【老年患者用药】
健康老年志愿者（≧65岁）的西地那非清除率降低。血药浓度较高，可能同时增加不良事件的发生，故起始剂量以25MG为宜。
副作用
1、头痛。临床试验中发现，约有1%的人服药后出现头痛，且服用剂量越大愈烈。
2、眼花。约有0.3%的服药者可发生短暂的视力模糊，有的还会出现看见蓝光的幻觉。
3、昏晕。可能造成血压骤降，如同时服用硝酸甘油等药物，常会立即头昏甚至晕倒。
4、掩盖心血管疾病。阳痿可能是心脏疾病、糖尿病或癌症的先兆，服用该药可能掩盖真正的病情。
5、血压降低。伟哥可引起血压降低，而含三硝酸甘油或硝酸盐等心脏病药物也会降低血压，故伟哥与这些药混用时血压会大大降低，有时可能危及生命。
7、青光眼。眼科专家警告，服用伟哥可导致血压下降，但青光眼患者眼压较高，有3%～5%的人可能出现急性青光眼，可使人一夜失明，即使治好也不能恢复原来视力。
8、暂时性耳聋。FDA报道，伟哥可致聋，约1/3为暂时性耳聋。
9、加重睡眠呼吸暂停。梗阻性睡眠呼吸暂停是由于在睡眠中喉部软组织塌陷，阻塞气道导致短时间的呼吸停止而产生的常见病症。
包装规格：（提示：以下二种产品用法以药品说明书为准）
伟哥 西地那非片
sildeHEXL Tabletten：100mg*12片/盒
厂家： 德国Hexal

阿伐那非片STENDRA (avanafil)Spedra
50mg*12片/盒
100mg*12片/盒
200mg*12片/盒
厂家：德国柏林化工

Sildenafil 100mg film-coated tablets
1. Name of the medicinal product
Sildenafil Zentiva 100mg film-coated tablets
2. Qualitative and quantitative composition
Each film-coated tablet contains 100mg of sildenafil (as 140.48mg sildenafil citrate).
Excipients with known effect: each sildenafil 100mg film-coated tablet contains 7.44mg of lactose monohydrate.
For the full list of excipients, see section 6.1.
3. Pharmaceutical form
Film-coated tablet
Blue coloured round, biconvex, scored approx. 12.00mm in diameter film-coated tablets debossed with 126 on one side and J on the other side with the score line. The tablet can be divided into equal doses.
4. Clinical particulars
4.1 Therapeutic indications
Sildenafil is indicated in adult of men with erectile dysfunction, which is the inability to achieve or maintain a penile erection sufficient for satisfactory sexual performance.
In order for sildenafil to be effective, sexual stimulation is required.
4.2 Posology and method of administration
Posology
Use in adults:
The recommended dose is 50mg taken as needed approximately one hour before sexual activity. Based on efficacy and tolerability, the dose may be increased to 100mg or decreased to 25mg. The maximum recommended dose is 100mg. The maximum recommended dosing frequency is once per day. If sildenafil is taken with food, the onset of activity may be delayed compared to the fasted state (see section 5.2).
Special populations
Elderly patients
Dosage adjustments are not required in elderly patients (≥65 years old).
Patients with renal impairment:
The dosing recommendations described in 'Use in adults' apply to patients with mild to moderate renal impairment (creatinine clearance = 30 - 80 ml/min).
Since sildenafil clearance is reduced in patients with severe renal impairment (creatinine clearance <30 ml/min) a 25mg dose should be considered. Based on efficacy and tolerability, the dose may be increased step-wise to 50mg up to 100mg as necessary.
Patients with hepatic impairment:
Since sildenafil clearance is reduced in patients with hepatic impairment (e.g. cirrhosis) a 25mg dose should be considered. Based on efficacy and tolerability, the dose may be increased step-wise to 50mg up to 100mg as necessary.
Paediatric population
Sildenafil is not indicated for individuals below 18 years of age.
Use in patients taking other medicinal products:
With the exception of ritonavir for which co-administration with sildenafil is not advised (see section 4.4) a starting dose of 25mg should be considered in patients receiving concomitant treatment with CYP3A4 inhibitors (see section 4.5).
In order to minimize the potential of developing postural hypotension in patients receiving alpha-blocker treatment, patients should be stabilised on alpha-blocker therapy prior to initiating sildenafil treatment. In addition, initiation of sildenafil at a dose of 25mg should be considered (see sections 4.4 and 4.5).
Method of administration
For oral use.
4.3 Contraindications
Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.
Consistent with its known effects on the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway (see section 5.1), sildenafil was shown to potentiate the hypotensive effects of nitrates, and its co-administration with nitric oxide donors (such as amyl nitrite) or nitrates in any form is therefore contraindicated.
Agents for the treatment of erectile dysfunction, including sildenafil, should not be used in men for whom sexual activity is inadvisable (e.g. patients with severe cardiovascular disorders such as unstable angina or severe cardiac failure).
Sildenafil is contraindicated in patients who have loss of vision in one eye because of non-arteritic anterior ischaemic optic neuropathy (NAION), regardless of whether this episode was in connection or not with previous PDE5 inhibitor exposure (see section 4.4).
The safety of sildenafil has not been studied in the following sub-groups of patients and its use is therefore contraindicated: severe hepatic impairment, hypotension (blood pressure <90/50 mmHg), recent history of stroke or myocardial infarction and known hereditary degenerative retinal disorders such as retinitis pigmentosa (a minority of these patients have genetic disorders of retinal phosphodiesterases).
4.4 Special warnings and precautions for use
A medical history and physical examination should be undertaken to diagnose erectile dysfunction and determine potential underlying causes, before pharmacological treatment is considered.
Cardiovascular risk factors
Prior to initiating any treatment for erectile dysfunction, physicians should consider the cardiovascular status of their patients, since there is a degree of cardiac risk associated with sexual activity. Sildenafil has vasodilator properties, resulting in mild and transient decreases in blood pressure (see section 5.1). Prior to prescribing sildenafil, physicians should carefully consider whether their patients with certain underlying conditions could be adversely affected by such vasodilatory effects, especially in combination with sexual activity. Patients with increased susceptibility to vasodilators include those with left ventricular outflow obstruction (e.g., aortic stenosis, hypertrophic obstructive cardiomyopathy), or those with the rare syndrome of multiple system atrophy manifesting as severely impaired autonomic control of blood pressure.
Sildenafil potentiates the hypotensive effect of nitrates (see section 4.3).
Serious cardiovascular events, including myocardial infarction, unstable angina, sudden cardiac death, ventricular arrhythmia, cerebrovascular haemorrhage, transient ischaemic attack, hypertension and hypotension have been reported post-marketing in temporal association with the use of sildenafil. Most, but not all, of these patients had pre-existing cardiovascular risk factors. Many events were reported to occur during or shortly after sexual intercourse and a few were reported to occur shortly after the use of sildenafil without sexual activity. It is not possible to determine whether these events are related directly to these factors or to other factors.
Priapism
Agents for the treatment of erectile dysfunction, including sildenafil, should be used with caution in patients with anatomical deformation of the penis (such as angulation, cavernosal fibrosis or Peyronie's disease), or in patients who have conditions which may predispose them to priapism (such as sickle cell anaemia, multiple myeloma or leukaemia).
Concomitant use with other treatments for erectile dysfunction
The safety and efficacy of combinations of sildenafil with other treatments for erectile dysfunction have not been studied. Therefore the use of such combinations is not recommended.
Effects on vision
Cases of visual defects have been reported spontaneously in connection with the intake of sildenafil and other PDE5 inhibitors (see section 4.8). Cases of non-arteritic anterior ischaemic optic neuropathy, a rare condition, have been reported spontaneously and in an observational study in connection with the intake of sildenafil and other PDE5 inhibitors (see section 4.8). Patients should be advised that in the event of any sudden visual defect, they should stop taking sildenafil and consult a physician immediately (see section 4.3).
Concomitant use with ritonavir
Co-administration of sildenafil with ritonavir is not advised (see section 4.5).
Concomitant use with alpha-blockers
Caution is advised when sildenafil is administered to patients taking an alpha-blocker, as the co-administration may lead to symptomatic hypotension in a few susceptible individuals (see section 4.5). This is most likely to occur within 4 hours post sildenafil dosing. In order to minimise the potential for developing postural hypotension, patients should be hemodynamically stable on alpha-blocker therapy prior to initiating sildenafil treatment. Initiation of sildenafil at a dose of 25mg should be considered (see section 4.2). In addition, physicians should advise patients what to do in the event of postural hypotensive symptoms.
Effect on bleeding
Studies with human platelets indicate that sildenafil potentiates the antiaggregatory effect of sodium nitroprusside in vitro. There is no safety information on the administration of sildenafil to patients with bleeding disorders or active peptic ulceration. Therefore sildenafil should be administered to these patients only after careful benefit-risk assessment.
The film coating of the sildenafil film-coated tablet contains lactose. Sildenafil should not be administered to men with rare hereditary problems of galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption.
Women
Sildenafil is not indicated for use by women.
4.5 Interaction with other medicinal products and other forms of interaction
Effects of other medicinal products on sildenafil
In vitro studies:
Sildenafil metabolism is principally mediated by the cytochrome P450 (CYP) isoforms 3A4 (major route) and 2C9 (minor route). Therefore, inhibitors of these isoenzymes may reduce sildenafil clearance.
In vivo studies:
Population pharmacokinetic analysis of clinical trial data indicated a reduction in sildenafil clearance when co-administered with CYP3A4 inhibitors (such as ketoconazole, erythromycin, cimetidine). Although no increased incidence of adverse events was observed in these patients, when sildenafil is administered concomitantly with CYP3A4 inhibitors, a starting dose of 25 mg should be considered.
Co-administration of the HIV protease inhibitor ritonavir, which is a highly potent P450 inhibitor, at steady state (500mg twice daily) with sildenafil (100mg single dose) resulted in a 300% (4-fold) increase in sildenafil Cmax and a 1,000% (11-fold) increase in sildenafil plasma AUC. At 24 hours, the plasma levels of sildenafil were still approximately 200ng/ml, compared to approximately 5ng/ml when sildenafil was administered alone. This is consistent with ritonavir's marked effects on a broad range of P450 substrates. Sildenafil had no effect on ritonavir pharmacokinetics. Based on these pharmacokinetic results co-administration of sildenafil with ritonavir is not advised (see section 4.4) and in any event the maximum dose of sildenafil should under no circumstances exceed 25 mg within 48 hours.
Co-administration of the HIV protease inhibitor saquinavir, a CYP3A4 inhibitor, at steady state (1200mg three times a day) with sildenafil (100mg single dose) resulted in a 140% increase in sildenafil Cmax and a 210% increase in sildenafil AUC. Sildenafil had no effect on saquinavir pharmacokinetics (see section 4.2). Stronger CYP3A4 inhibitors such as ketoconazole and itraconazole would be expected to have greater effects.
When a single 100mg dose of sildenafil was administered with erythromycin, a specific CYP3A4 inhibitor, at steady state (500mg twice daily. for 5 days), there was a 182% increase in sildenafil systemic exposure (AUC). In normal healthy male volunteers, there was no evidence of an effect of azithromycin (500mg daily for 3 days) on the AUC, Cmax, tmax, elimination rate constant, or subsequent half-life of sildenafil or its principal circulating metabolite. Cimetidine (800mg), a cytochrome P450 inhibitor and non-specific CYP3A4 inhibitor, caused a 56% increase in plasma sildenafil concentrations when co-administered with sildenafil (50mg) to healthy volunteers.
Grapefruit juice is a weak inhibitor of CYP3A4 gut wall metabolism and may give rise to modest increases in plasma levels of sildenafil.
Single doses of antacid (magnesium hydroxide/aluminium hydroxide) did not affect the bioavailability of sildenafil.
Although specific interaction studies were not conducted for all medicinal products, population pharmacokinetic analysis showed no effect of concomitant treatment on sildenafil pharmacokinetics when grouped as CYP2C9 inhibitors (such as tolbutamide, warfarin, phenytoin), CYP2D6 inhibitors (such as selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and related diuretics, loop and potassium sparing diuretics, angiotensin converting enzyme inhibitors, calcium channel blockers, beta-adrenoreceptor antagonists or inducers of CYP450 metabolism (such as rifampicin, barbiturates).
Nicorandil is a hybrid of potassium channel activator and nitrate. Due to the nitrate component it has the potential to result in a serious interaction with sildenafil.
Effects of sildenafil on other medicinal products
In vitro studies:
Sildenafil is a weak inhibitor of the cytochrome P450 isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 > 150 μM). Given sildenafil peak plasma concentrations of approximately 1 μM after recommended doses, it is unlikely that sildenafil will alter the clearance of substrates of these isoenzymes.
There are no data on the interaction of sildenafil and non-specific phosphodiesterase inhibitors such as theophylline or dipyridamole.
In vivo studies:
Consistent with its known effects on the nitric oxide/cGMP pathway (see section 5.1), sildenafil was shown to potentiate the hypotensive effects of nitrates, and its co-administration with nitric oxide donors or nitrates in any form is therefore contraindicated (see section 4.3).
Concomitant administration of sildenafil to patients taking alpha-blocker therapy may lead to symptomatic hypotension in a few susceptible individuals. This is most likely to occur within 4 hours post sildenafil dosing (see sections 4.2 and 4.4). In three specific drug-drug interaction studies, the alpha-blocker doxazosin (4mg and 8mg) and sildenafil (25mg, 50mg, or 100mg) were administered simultaneously to patients with benign prostatic hyperplasia (BPH) stabilized on doxazosin therapy. In these study populations, mean additional reductions of supine blood pressure of 7/7mmHg, 9/5mmHg, and 8/4 mmHg, and mean additional reductions of standing blood pressure of 6/6mmHg, 11/4mmHg, and 4/5mmHg, respectively, were observed. When sildenafil and doxazosin were administered simultaneously to patients stabilized on doxazosin therapy, there were infrequent reports of patients who experienced symptomatic postural hypotension. These reports included dizziness and light-headedness, but not syncope.
No significant interactions were shown when sildenafil (50mg) was co-administered with tolbutamide (250mg) or warfarin (40mg), both of which are metabolised by CYP2C9.
Sildenafil (50mg) did not potentiate the increase in bleeding time caused by acetyl salicylic acid (150mg).
Sildenafil (50mg) did not potentiate the hypotensive effects of alcohol in healthy volunteers with mean maximum blood alcohol levels of 80mg/dl.
Pooling of the following classes of antihypertensive medication: diuretics, beta-blockers, ACE inhibitors, angiotensin II antagonists, antihypertensive medicinal products (vasodilator and centrally-acting), adrenergic neurone blockers, calcium channel blockers and alpha-adrenoceptor blockers, showed no difference in the side effect profile in patients taking sildenafil compared to placebo treatment. In a specific interaction study, where sildenafil (100mg) was co-administered with amlodipine in hypertensive patients, there was an additional reduction on supine systolic blood pressure of 8 mmHg. The corresponding additional reduction in supine diastolic blood pressure was 7 mmHg. These additional blood pressure reductions were of a similar magnitude to those seen when sildenafil was administered alone to healthy volunteers (see section 5.1).
Sildenafil (100mg) did not affect the steady state pharmacokinetics of the HIV protease inhibitors, saquinavir and ritonavir, both of which are CYP3A4 substrates.
4.6 Fertility, pregnancy and lactation
Sildenafil is not indicated for use by women.
There are no adequate and well-controlled studies in pregnant or breastfeeding women.
No relevant adverse effects were found in reproduction studies in rats and rabbits following oral administration of sildenafil.
There was no effect on sperm motility or morphology after single 100 mg oral doses of sildenafil in healthy volunteers (see section 5.1).
4.7 Effects on ability to drive and use machines
No studies on the effects on the ability to drive and use machines have been performed.
As dizziness and altered vision were reported in clinical trials with sildenafil, patients should be aware of how they react to sildenafil before driving or operating machinery.
4.8 Undesirable effects
Summary of the safety profile
The safety profile of sildenafil is based on 8691 patients who received the recommended dosing regimen in 67 placebo-controlled clinical studies. The most commonly reported adverse reactions in clinical studies among sildenafil treated patients were headache, flushing, dyspepsia, visual disorders, nasal congestion, dizziness and visual colour distortion.
Adverse reactions from post-marketing surveillance has been gathered covering an estimated period >9 years. Because not all adverse reactions are reported, the frequencies of these reactions cannot be reliably determined.
Tabulated list of adverse reactions
In the table below all medically important adverse reactions, which occurred in clinical trials at an incidence greater than placebo are listed by system organ class and frequency (very common (≥1/10), common (≥1/100 to <1/10), uncommon (≥1/1,000 to <1/100), rare (≥1/10,000 to <1/1,000).
In addition, the frequency of medically important adverse reactions reported from post-marketing experience is included as not known.
Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.
Table 1: Medically important adverse reactions reported at an incidence greater than placebo in controlled clinical studies and medically important adverse reactions reported through post-marketing surveillance.

MedDRA system organ class	Frequency	Undesirable effect
Immune system disorders=	rare	Hypersensitivity reactions
Nervous system disorders	very common	Headache
	common	Dizziness
	uncommon	Somnolence, Hypoaesthesia
	rare	Cerebrovascular accident, Syncope
	not known	Transient ischaemic attack, Seizure, Seizure recurrence
Eye disorders Not known	common	Visual disorders, visual colour distortion
	uncommon	Conjunctival disorders, Eye disorders, Lacrimation disorders, Other Eye disorders
	not known	Non-arteritic anterior ischaemic optic neuropathy (NAION), Retinal vascular occlusion, Visual field defect
Ear and labyrinth disorders	uncommon	Vertigo, Tinnitus
	rare	Deafness
Cardiac disorders	uncommon	Palpitations, Tachycardia
	rare	Myocardial infarction, Atrial fibrillation
	not known	Ventricular arrhythmia, Angina unstable, Sudden cardiac death
Vascular disorders	common	Flushing
	rare	Hypertension Hypotension
Respiratory, thoracic and mediastinal disorders	common	Nasal congestion
	rare	Epistaxis
Gastrointestinal disorders	common	Dyspepsia
	uncommon	Vomiting, Nausea, Dry mouth
Skinand subcutaneous tissue disorders	uncommon	Skin rash
	not known	Steven Johnson Syndrome (SJS), Toxic Epidermal Necrolysis (TEN)
Musculoskeletal and connective tissue disorders	uncommon	Myalgia
Renal and urinary disorders	uncommon	Haematuria
Reproductive system and breast disorders	uncommon	Haematospermia, Penile haemorrhage
	not known	Priapism, Prolonged erection
General disorders and administration site conditions	uncommon	Chest pain, Fatigue
Investigations	uncommon	Heart rate increased

Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard.
4.9 Overdose
In single dose volunteer studies of doses up to 800mg, adverse reactions were similar to those seen at lower doses, but the incidence rates and severities were increased. Doses of 200mg did not result in increased efficacy but the incidence of adverse reactions (headache, flushing, dizziness, dyspepsia, nasal congestion, altered vision) was increased.
In cases of overdose, standard supportive measures should be adopted as required. Renal dialysis is not expected to accelerate clearance as sildenafil is highly bound to plasma proteins and not eliminated in the urine.
5. Pharmacological properties
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Urologicals; Drugs used in erectile dysfunction. ATC Code: G04B E03.
Mechanism of action
Sildenafil is an oral therapy for erectile dysfunction. In the natural setting, i.e. with sexual stimulation, it restores impaired erectile function by increasing blood flow to the penis.
The physiological mechanism responsible for erection of the penis involves the release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. Nitric oxide then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood.
Sildenafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) in the corpus cavernosum, where PDE5 is responsible for degradation of cGMP. Sildenafil has a peripheral site of action on erections. Sildenafil has no direct relaxant effect on isolated human corpus cavernosum but potently enhances the relaxant effect of NO on this tissue. When the NO/cGMP pathway is activated, as occurs with sexual stimulation, inhibition of PDE5 by sildenafil results in increased corpus cavernosum levels of cGMP. Therefore sexual stimulation is required in order for sildenafil to produce its intended beneficial pharmacological effects.
Pharmacodynamic effects
Studies in vitro have shown that sildenafil is selective for PDE5, which is involved in the erection process. Its effect is more potent on PDE5 than on other known phosphodiesterases. There is a 10-fold selectivity over PDE6 which is involved in the phototransduction pathway in the retina. At maximum recommended doses, there is an 80-fold selectivity over PDE1, and over 700-fold over PDE2, 3, 4, 7, 8, 9, 10 and 11. In particular, sildenafil has greater than 4,000-fold selectivity for PDE5 over PDE3, the cAMP-specific phosphodiesterase isoform involved in the control of cardiac contractility.
Clinical efficacy and safety
Two clinical studies were specifically designed to assess the time window after dosing during which sildenafil could produce an erection in response to sexual stimulation. In a penile plethysmography (RigiScan) study of fasted patients, the median time to onset for those who obtained erections of 60% rigidity (sufficient for sexual intercourse) was 25 minutes (range 12-37 minutes) on sildenafil. In a separate RigiScan study, sildenafil was still able to produce an erection in response to sexual stimulation 4-5 hours post-dose.
Sildenafil causes mild and transient decreases in blood pressure which, in the majority of cases, do not translate into clinical effects. The mean maximum decreases in supine systolic blood pressure following 100mg oral dosing of sildenafil was 8.4 mmHg. The corresponding change in supine diastolic blood pressure was 5.5 mmHg. These decreases in blood pressure are consistent with the vasodilatory effects of sildenafil, probably due to increased cGMP levels in vascular smooth muscle. Single oral doses of sildenafil up to 100mg in healthy volunteers produced no clinically relevant effects on ECG.
In a study of the hemodynamic effects of a single oral 100mg dose of sildenafil in 14 patients with severe coronary artery disease (CAD) (>70% stenosis of at least one coronary artery), the mean resting systolic and diastolic blood pressures decreased by 7% and 6% respectively compared to baseline. Mean pulmonary systolic blood pressure decreased by 9%. Sildenafil showed no effect on cardiac output, and did not impair blood flow through the stenosed coronary arteries.
A double blind, placebo controlled exercise stress trial evaluated 144 patients with erectile dysfunction and chronic stable angina, who regularly received anti-anginal medicinal products (except nitrates). The results demonstrated no clinically relevant differences between sildenafil and placebo in time to limiting angina.
Mild and transient differences in colour discrimination (blue/green) were detected in some subjects using the Farnsworth-Munsell 100 hue test at 1 hour following a 100mg dose, with no effects evident after 2 hours post-dose. The postulated mechanism for this change in colour discrimination is related to inhibition of PDE6, which is involved in the phototransduction cascade of the retina. Sildenafil has no effect on visual acuity or contrast sensitivity. In a small size placebo-controlled study of patients with documented early age-related macular degeneration (n=9), sildenafil (single dose, 100mg) demonstrated no significant changes in the visual tests conducted (visual acuity, Amsler grid, colour discrimination simulated traffic light, Humphrey perimeter and photostress).
There was no effect on sperm motility or morphology after single 100mg oral doses of sildenafil in healthy volunteers (see section 4.6).
Further information on clinical trials
In clinical trials sildenafil was administered to more than 8000 patients aged 19-87. The following patient groups were represented: elderly (19.9%), patients with hypertension (30.9%), diabetes mellitus (20.3%), ischaemic heart disease (5.8%), hyperlipidaemia (19.8%), spinal cord injury (0.6%), depression (5.2%), transurethral resection of the prostate (3.7%), radical prostatectomy (3.3%). The following groups were not well represented or excluded from clinical trials: patients with pelvic surgery, patients post-radiotherapy, patients with severe renal or hepatic impairment and patients with certain cardiovascular conditions (see section 4.3).
In fixed dose studies, the proportions of patients reporting that treatment improved their erections were 62% (25mg), 74% (50mg) and 82% (100mg) compared to 25% on placebo. In controlled clinical trials, the discontinuation rate due to sildenafil was low and similar to placebo. Across all trials, the proportion of patients reporting improvement on sildenafil were as follows: psychogenic erectile dysfunction (84%), mixed erectile dysfunction (77%), organic erectile dysfunction (68%), elderly (67%), diabetes mellitus (59%), ischaemic heart disease (69%), hypertension (68%), TURP (61%), radical prostatectomy (43%), spinal cord injury (83%), depression (75%). The safety and efficacy of sildenafil was maintained in long-term studies.
Paediatric population
The European Medicines Agency has waived the obligation to submit the results of studies with sildenafil in all subsets of the paediatric population for the treatment of erectile dysfunction. See 4.2 for information on paediatric use.
5.2 Pharmacokinetic properties
Absorption:
Sildenafil is rapidly absorbed. Maximum observed plasma concentrations are reached within 30 to 120 minutes (median 60 minutes) of oral dosing in the fasted state. The mean absolute oral bioavailability is 41% (range 25-63%). After oral dosing of sildenafil AUC and Cmax increase in proportion with dose over the recommended dose range (25-100mg).
When sildenafil is taken with food, the rate of absorption is reduced with a mean delay in tmax of 60 minutes and a mean reduction in Cmax of 29%.
Distribution:
The mean steady state volume of distribution (Vd) for sildenafil is 105 l, indicating distribution into the tissues. After a single oral dose of 100mg, the mean maximum total plasma concentration of sildenafil is approximately 440 ng/ml (CV 40%). Since sildenafil (and its major circulating N-desmethyl metabolite) is 96% bound to plasma proteins, this results in the mean maximum free plasma concentration for sildenafil of 18 ng/ml (38 nM). Protein binding is independent of total drug concentrations.
In healthy volunteers receiving sildenafil (100mg single dose), less than 0.0002% (average 188 ng) of the administered dose was present in ejaculate 90 minutes after dosing.
Biotransformation:
Sildenafil is cleared predominantly by the CYP3A4 (major route) and CYP2C9 (minor route) hepatic microsomal isoenzymes. The major circulating metabolite results from N-demethylation of sildenafil. This metabolite has a phosphodiesterase selectivity profile similar to sildenafil and an in vitro potency for PDE5 approximately 50% that of the parent drug. Plasma concentrations of this metabolite are approximately 40% of those seen for sildenafil. The N-desmethyl metabolite is further metabolised, with a terminal half-life of approximately 4 h.
Elimination:
The total body clearance of sildenafil is 41 l/h with a resultant terminal phase half-life of 3-5 h. After either oral or intravenous administration, sildenafil is excreted as metabolites predominantly in the faeces (approximately 80% of administered oral dose) and to a lesser extent in the urine (approximately 13% of administered oral dose).
Pharmacokinetics in special patient groups
Elderly:
Healthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil, resulting in approximately 90% higher plasma concentrations of sildenafil and the active N-desmethyl metabolite compared to those seen in healthy younger volunteers (18-45 years). Due to age-differences in plasma protein binding, the corresponding increase in free sildenafil plasma concentration was approximately 40%.
Renal insufficiency:
In volunteers with mild to moderate renal impairment (creatinine clearance = 30-80 ml/min), the pharmacokinetics of sildenafil were not altered after receiving a 50mg single oral dose. The mean AUC and Cmax of the N-desmethyl metabolite increased 126% and 73% respectively, compared to age-matched volunteers with no renal impairment. However, due to high inter-subject variability, these differences were not statistically significant. In volunteers with severe renal impairment (creatinine clearance <30 ml/min), sildenafil clearance was reduced, resulting in mean increases in AUC and Cmax of 100% and 88% respectively compared to age-matched volunteers with no renal impairment. In addition, N-desmethyl metabolite AUC and Cmax values were significantly increased 79% and 200% respectively.
Hepatic insufficiency:
In volunteers with mild to moderate hepatic cirrhosis (Child-Pugh A and B) sildenafil clearance was reduced, resulting in increases in AUC (84%) and Cmax (47%) compared to age-matched volunteers with no hepatic impairment. The pharmacokinetics of sildenafil in patients with severely impaired hepatic function have not been studied.
5.3 Preclinical safety data
Non-clinical data revealed no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, carcinogenic potential, and toxicity to reproduction and development.
6. Pharmaceutical particulars
6.1 List of excipients
Tablet core:
microcrystalline cellulose
calcium hydrogen phosphate (anhydrous)
croscarmellose sodium
magnesium stearate
Film coat:
lactose monohydrate
hypromellose
titanium dioxide (E171)
triacetin
indigo carmine aluminium lake (E132)
6.2 Incompatibilities
Not applicable.
6.3 Shelf life
2 years.
6.4 Special precautions for storage
This medicinal product does not require any special storage conditions.
6.5 Nature and contents of container
PVC/Aluminium foil blisters in cartons of 1, 2, 4, 8, 12 or 24 film-coated tablets.
Not all pack sizes may be marketed.
6.6 Special precautions for disposal and other handling
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
7. Marketing authorisation holder
Winthrop Pharmaceuticals UK Ltd
One Onslow Street
Guildford Surrey GU1 4YS
United Kingdom
Trading as:
Zentiva, One Onslow Street, Guildford, Surrey, GU1 4YS, UK
8. Marketing authorisation number(s)
 PL 17780/0625
9. Date of first authorisation/renewal of the authorisation
04/04/2013
10. Date of revision of the text
25/02/2014