1. Name Of The Medicinal Product
NIFOPRESS RETARD TABLETS 20 mg
2. Qualitative And Quantitative Composition
Each modified-release tablet contains 20 mg nifedipine
For excipients see Section 6.1
3. Pharmaceutical Form
Modified-release tablets.
Nifopress Retard are circular biconvex coated tablets, pink-brownish in colour embossed with "NR" on one face and "20" on the other face.
4. Clinical Particulars
4.1 Therapeutic Indications
Nifedipine is an anti-anginal vasodilator. As such it is indicated for the prophylaxis of angina pectoris, for the treatment of mild to moderate hypertension and for Raynaud's phenomenon.
Further information:
Nifedipine has no therapeutic anti-arrhythmic effect.
Since nifedipine does not cause a rise in intraocular pressure, it can be used in patients with glaucoma.
Nifedipine can be used in patients with obstructive airways disease with coexisting hypertension or angina pectoris.
Long term metabolic effects have not been observed.
4.2 Posology And Method Of Administration
Nifopress Retard Tablets are for oral administration. They should be taken with a little fluid during or after food.
Adults: The usual effective dose is one tablet (20mg) twice daily. This may be adjusted within the range 10mg to 40mg twice daily.
Treatment may be continued indefinitely.
Children: There are no recommendations for use in children.
4.3 Contraindications
Nifopress Retard must not be administered to patients with known hypersensitivity to nifedipine, or to other dihydropyridines because of the theoretical risk of cross-reactivity, or to any of the excipients.
Nifopress Retard is contraindicated in pregnancy before week 20 and during breastfeeding (see Sections 4.4, 4.6 and 5.3).
Nifopress Retard must not be used in cases of cardiogenic shock, clinically significant aortic stenosis, unstable angina, or during or within 4 weeks of a myocardial infarction.
Nifopress Retard should not be used for the treatment of acute attacks of angina.
The safety of Nifopress Retard in malignant hypertension has not been established.
Nifopress Retard should not be used for secondary prevention of myocardial infarction.
Nifopress Retard should not be administered concomitantly with rifampicin since effective plasma levels of nifedipine may not be achieved owing to enzyme induction (see Section 4.5).
4.4 Special Warnings And Precautions For Use
Ischaemic pain has been reported in a small proportion of patients within 1 to 4 hours of the introduction of nifedipine therapy. Although a 'steal' effect has not been demonstrated patients experiencing this effect should discontinue nifedipine.
Nifopress Retard is not a beta-blocker and therefore gives no protection against the dangers of abrupt beta-blocker withdrawal; any such withdrawal should be a gradual reduction of the dose of beta-blocker preferably over 8 - 10 days.
Nifopress Retard may be used in combination with beta-blocking drugs and other antihypertensive agents but the possibility of an additive effect resulting in postural hypotension should be borne in mind. Nifopress retard will not prevent possible rebound effects after cessation of other antihypertensive therapy.
Care must be exercised in patients with very low blood pressure (severe hypotension with systolic pressure less than 90 mm Hg).
Careful monitoring of blood pressure must be exercised when administering nifedipine with I.V. magnesium sulphate, owing to the possibility of an excessive fall in blood pressure, which could harm both mother and foetus. For further information regarding use in pregnancy, refer to section 4.6.
In patients with impaired liver function, careful monitoring, and in severe cases, a dose reduction may be necessary.
Nifopress Retard should be used with caution in patients whose cardiac reserve is poor. Deterioration of heart failure has occasionally been observed with nifedipine.
The use of Nifopress Retard in diabetic patients may require adjustment of their control.
In dialysis patients with malignant hypertension and hypovolaemia, a marked decrease in blood pressure can occur.
Nifedipine is metabolised via the cytochrome P450 3A4 system. Drugs that are known to either inhibit or to induce this enzyme system may therefore alter the first pass or the clearance of nifedipine (see Section 4.5).
Drugs that are known inhibitors of the cytochrome P450 3A4 system, and which may therefore lead to increased plasma concentrations of nifedipine include, for example:
- macrolide antibiotics (e.g., erythromycin)
- anti-HIV protease inhibitors (e.g., ritonavir)
- azole antimycotics (e.g., ketoconazole)
- the antidepressants, nefazodone and fluoxetine
- quinupristin/dalfopristin
- valproic acid
- cimetidine
Upon co-administration with these drugs, the blood pressure should be monitored and, if necessary, a reduction of the nifedipine dose should be considered (see section 4.5).
Since this medicinal product contains lactose, patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.
4.5 Interaction With Other Medicinal Products And Other Forms Of Interaction
Drugs that affect nifedipine:
Nifedipine is metabolised via the cytochrome P450 3A4 system, located both in the intestinal mucosa and in the liver. Drugs that are known to either inhibit or to induce this enzyme system may therefore alter the first pass (after oral administration) or the clearance of nifedipine. (see section 4.4)
The extent as well as the duration of interactions should be taken into account when administering nifedipine together with the following drugs:
Rifampicin: Rifampicin strongly induces the cytochrome P450 3A4 system. Upon co-administration with rifampicin, the bioavailability of nifedipine is distinctly reduced and thus its efficacy weakened. The use of nifedipine in combination with rifampicin is therefore contraindicated (see Section 4.3).
Upon co-administration of known inhibitors of the cytochrome P450 3A4 system, the blood pressure should be monitored and, if necessary, a reduction in the nifedipine dose considered (see Sections 4.2 and 4.4). In the majority of these cases, no formal studies to assess the potential for a drug interaction between nifedipine and the drug(s) listed have been undertaken, thus far.
Drugs increasing nifedipine exposure:
- macrolide antibiotics (e.g., erythromycin)
- anti-HIV protease inhibitors (e.g., ritonavir)
- azole anti-mycotics (e.g., ketoconazole)
- fluoxetine
- nefazodone
- quinupristin/dalfopristin
- cisapride
- valproic acid
- cimetidine
- diltiazem
Upon co-administration of inducers of the cytochrome P450 3A4 system, the clinical response to nifedipine should be monitored and, if necessary, an increase in the nifedipine dose considered. If the dose of nifedipine is increased during co-administration of both drugs, a reduction of the nifedipine dose should be considered when the treatment is discontinued.
Drugs decreasing nifedipine exposure:
- rifampicin (see above)
- phenytoin
-carbamazepine
- phenobarbital
Effects of nifedipine on other drugs
Nifedipine may increase the blood pressure lowering effect of concomitant applied antihypertensives.
When nifedipine is administered simultaneously with beta-receptor blockers the patient should be carefully monitored, since deterioration of heart failure is also known to develop in isolated cases.
Digoxin: The simultaneous administration of nifedipine and digoxin may lead to reduced digoxin clearance and, hence, an increase in the plasma digoxin level. The patient should therefore be subjected to precautionary checks for symptoms of digoxin overdosage and, if necessary, the glycoside dose should be reduced.
Quinidine: Co-administration of nifedipine with quinidine may lower plasma quinidine levels, and after discontinuation of nifedipine, a distinct increase in plasma quinidine levels may be observed in individual cases. Consequently, when nifedipine is either additionally administered or discontinued, monitoring of the quinidine plasma concentration, and if necessary, adjustment of the quinidine dose are recommended. Blood pressure should be carefully monitored and, if necessary, the dose of nifedipine should be decreased.
Tacrolimus: Tacrolimus is metabolised via the cytochrome P450 3A4 system. Published data indicate that the dose of tacrolimus administered simultaneously with nifedipine may be reduced in individual cases. Upon co-administration of both drugs, the tacrolimus plasma concentrations should be monitored and, if necessary, a reduction in the tacrolimus dose considered.
Drug food interactions:
Grapefruit juice inhibits the cytochrome P450 3A4 system. Administration of nifedipine together with grapefruit juice thus results in elevated plasma concentrations and prolonged action of nifedipine due to a decreased first pass metabolism or reduced clearance. As a consequence, the blood pressure lowering effect of nifedipine may be increased. After regular intake of grapefruit juice, this effect may last for at least three days after the last ingestion of grapefruit juice. Ingestion of grapefruit/grapefruit juice is therefore to be avoided while taking nifedipine (see Section 4.2).
Other forms of interaction
Nifedipine may increase the spectrophotometric values of urinary vanillylmandelic acid, falsely. However, HPLC measurements are unaffected.
4.6 Pregnancy And Lactation
Nifopress Retard is contraindicated in pregnancy before week 20. (see section 4.3).
In animal studies, nifedipine has been shown to produce embryotoxicity, foetotoxicity and teratogenicity (see Section 5.3 Preclinical safety data).
There are no adequate well controlled studies in pregnant women.
From the clinical evidence available a specific prenatal risk has not been identified, although an increase in perinatal asphyxia, caesarean delivery, as well as prematurity and intrauterine growth retardation have been reported. It is unclear whether these reports are due to the underlying hypertension, its treatment, or to a specific drug effect.
The available information is inadequate to rule out adverse drug effects on the unborn and newborn child. Therefore any use in pregnancy after week 20 requires a very careful individual risk benefit assessment and should only be considered if all other treatment options are either not indicated or have failed to be efficacious.
In single cases of in-vitro fertilisation calcium antagonists like nifedipine have been associated with reversible biochemical changes in the spermatozoa's head section that may result in impaired sperm function. In those men who are repeatedly unsuccessful in fathering a child by in vitro fertilisation, and where no other explanation can be found, calcium antagonists like nifedipine should be considered as possible causes.
Nifedipine passes into the breast milk. As there is no experience of possible effects on infants, breastfeeding should first be stopped if nifedipine treatment becomes necessary during the breastfeeding period.
4.7 Effects On Ability To Drive And Use Machines
Reactions to the drug, which vary in intensity from individual to individual, may impair the ability to drive or to operate machinery. This applies particularly at the start of treatment, on changing the medication and in combination with alcohol.
4.8 Undesirable Effects
Adverse drug reactions (ADRs) are listed below:
ADRs listed under "common" were observed with a frequency below 3% with the exception of oedema (9.9%) and headache (3.9%).
ADRs derived from post marketing reports are printed in bold italic.
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*= may result in life threatening outcome
In dialysis patients with malignant hypertension and hypovolaemia, a distinct fall in blood pressure can occur as a result of vasodilatation.
4.9 Overdose
Symptoms:
The following symptoms are observed in cases of severe nifedipine intoxication:
Disturbances of consciousness to the point of coma, a drop in blood pressure, tachycardia, bradycardia, hyperglycaemia, metabolic acidosis, hypoxia, cardiogenic shock with pulmonary oedema.
Treatment
As far as treatment is concerned, elimination of nifedipine and the restoration of stable cardiovascular conditions have priority. Elimination must be as complete as possible, including the small intestine, to prevent the otherwise inevitable subsequent absorption of the active substance.
The benefit of gastric decontamination is uncertain.
1. Consider activated charcoal (50 g for adults, 1 g/kg for children) if the patient presents within 1 hour of ingestion of a potentially toxic amount.
Although it may seem reasonable to assume that late administration of activated charcoal may be beneficial for sustained release (SR, MR) preparations, there is no evidence to support this.
2. Alternatively, consider gastric lavage in adults within 1 hour of a potentially life-threatening overdose.
3. Consider further doses of activated charcoal every 4 hours if a clinically significant amount of sustained release preparation has been ingested with a single dose of an osmotic laxative (e.g. sorbitol, lactulose or magnesium sulphate).
4. Asymptomatic patients should be observed for at least 4 hours after ingestion and for 12 hours if a sustained release preparation has been taken.
Haemodialysis serves no purpose as nifedipine is not dialysable.
Hypotension as a result of cardiogenic shock and arterial vasodilatation can be treated with calcium (10-20 ml of a 10 % calcium gluconate solution administered intravenously over 5-10 minutes). If the effects are inadequate, the treatment can be continued, with ECG monitoring. If an insufficient increase in blood pressure is achieved with calcium, vasoconstricting sympathomimetics such as dopamine or noradrenaline should be administered. The dosage of these drugs should be determined by the patient's response.
Symptomatic bradycardia may be treated with atropine, beta-sympathomimetics or a temporary cardiac pacemaker, as required.
Additional fluids should be administered with caution to avoid cardiac overload.
5. Pharmacological Properties
5.1 Pharmacodynamic Properties
ATC code: C08CA05
Nifedipine is a specific and potent calcium antagonist of the 1, 4-dihydropyridine type. Calcium antagonists reduce the transmembranal influx of calcium ions through the slow calcium channel into the cell. Nifedipine acts particularly on the cells of the myocardium and the smooth muscle cells of the coronary arteries and the peripheral resistance vessels.
In hypertension, the main action of Nifopress Retard is to cause peripheral vasodilatation and thus reduce peripheral resistance.
In angina, Nifopress retard reduces peripheral and coronary vascular resistance, leading to an increase in coronary blood flow, cardiac output and stroke volume, whilst decreasing after-load.
Additionally, nifedipine dilates submaximally both clear and atherosclerotic coronary arteries, thus protecting the heart against coronary artery spasm and improving perfusion to the ischaemic myocardium.
Nifedipine reduces the frequency of painful attacks and the ischaemic ECG changes irrespective of the relative contribution from coronary artery spasm or atherosclerosis.
Nifopress retard administered twice-daily provides 24-hour control of raised blood pressure. Nifopress retard causes reduction in blood pressure such that the percentage lowering is directly related to its initial level. In normotensive individuals, Nifopress retard has little or no effect on blood pressure.
5.2 Pharmacokinetic Properties
Absorption
After oral administration nifedipine is rapidly and almost completely absorbed. The systemic availability of orally administered nifedipine is 45 – 56 % owing to a first pass effect. Maximum plasma and serum concentrations are reached at 1.5 to 4.2 hours with Nifopress retard 20 mg tablets. Simultaneous food intake leads to delayed, but not reduced absorption.
Distribution
Nifedipine is about 95 % bound to plasma protein (albumin). The distribution half-life after intravenous administration was determined to be 5 to 6 minutes.
Biotransformation
After oral administration nifedipine is metabolized in the gut wall and in the liver, primarily by oxidative processes. These metabolites show no pharmacodynamic activity. Nifedipine is excreted in the form of its metabolites predominantly via the kidneys and about 5 – 15 % via the bile in the faeces. The unchanged substance is recovered only in traces (below 0.1 %) in the urine.
Elimination
The terminal elimination half-life is 6 - 11 hours (Nifopress retard), because of delayed absorption. No accumulation of the substance after the usual dose was reported during long-term treatment. In cases of impaired kidney function no substantial changes have been detected in comparison with healthy volunteers. In cases of impaired liver function the elimination half-life is distinctly prolonged and the total clearance is reduced. A dose reduction may be necessary in severe cases.
5.3 Preclinical Safety Data
Preclinical data reveal no special hazards for humans based on conventional studies of single and repeated dose toxicity, genotoxicity and carcinogenic potential.
Reproduction toxicology
Nifedipine has been shown to produce teratogenic findings in rats, mice and rabbits, including digital anomalies, malformation of the extremities, cleft palates, cleft sternum, and malformation of the ribs. Digital anomalies and malformation of the extremities are possibly a result of compromised uterine blood flow, but have also been observed in animals treated with nifedipine solely after the end of the organogenesis period.
Nifedipine administration was associated with a variety of embryotoxic, placentotoxic and foetotoxic effects, including stunted foetuses (rats, mice, rabbits), small placentas and underdeveloped chorionic villi (monkeys), embryonic and foetal deaths (rats, mice, rabbits) and prolonged pregnancy/decreased neonatal survival (rats; not evaluated in other species). The risk to humans cannot be ruled out if a sufficiently high systemic exposure is achieved, however, all of the doses associated with the teratogenic, embryotoxic or foetotoxic effects in animals were maternally toxic and were several times the recommended maximum dose for humans (see Section 4.6).
6. Pharmaceutical Particulars
6.1 List Of Excipients
Tablet core:
Polysorbate 80
Maize Starch
Microcrystalline Cellulose 101
Lactose
Magnesium Stearate
Tablet coating:
Sicopharm Rot30 (E172)
Polyethylene glycol 4000
Titanium dioxide
Hydroxpropylmethyl cellulose (E5)
6.2 Incompatibilities
None stated.
6.3 Shelf Life
Forty-eight months - Nifopress Retard Tablets should not be used after the 'Use Before' date given on the container.
6.4 Special Precautions For Storage
•Protect from light.
•Store below 25°C
6.5 Nature And Contents Of Container
PVC blisters (250µm)with Aluminium foil lids (20µm). Packs of 100 tablets contains 10 strips of 10 tablets
Tablets are in pack sizes of 56, 100 or 112 tablets.
6.6 Special Precautions For Disposal And Other Handling
No special instructions.
7. Marketing Authorisation Holder
Goldshield Group Limited
NLA Tower
Croydon
Surrey
CR0 0XT
Trading as: Goldshield Pharmaceuticals
8. Marketing Authorisation Number(S)
PL 10972/0052
9. Date Of First Authorisation/Renewal Of The Authorisation
26/09/1997 / 06/11/2006
10. Date Of Revision Of The Text
05/11/2010
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