Glyceryl trinitrate oral
- Drugs List
- Therapeutic Indications
- Precautions and Warnings
- Pregnancy and Lactation
- Side Effects
Tablet formulations of sublingual glyceryl trinitrate.
Prophylaxis of angina pectoris
Treatment of angina pectoris
Treatment of acute attacks of angina pectoris
When angina starts, 300 micrograms to 1 mg of glyceryl trinitrate should be taken. If symptoms do not resolve, glyceryl trinitrate may be repeated at 5 minute intervals for a total of three doses.
If symptoms have not resolved after a total of three doses, the patient should seek prompt medial attention.
Prophylaxis of angina pectoris
The recommended dose is 300 micrograms to 1 mg. May be used prior to activity which is likely to precipitate angina pectoris.
(See Dosage - Adults).
Children under 18 years
Hypertrophic obstructive cardiomyopathy
Narrow angle glaucoma
Raised intracranial pressure
Toxic pulmonary oedema
Precautions and Warnings
Low cardiac filling pressures
Predisposition to narrow angle glaucoma
Systolic blood pressure < 90mmHg
Glucose-galactose malabsorption syndrome
Severe hepatic impairment
Severe renal impairment
Lack of effect may indicate early myocardial infarction
Advise ability to drive/operate machinery may be affected by side effects
Advise patient to seek medical help if symptoms unresolved after 3 doses
Moisten buccal mucosa in dry mouth
Monitor patients at risk of glaucoma for increases in intraocular pressure
Cross tolerance to other nitrates may develop
Hypotensive effects may be potentiated by alcohol
Certain conditions or medications (with anticholinergic effects) may precipitate a dry mouth which can reduce the effectiveness of sublingual nitrates. If patient has dry mouth, prior to tablet insertion they should moisten buccal mucosa.
Patients particularly the elderly should be advised to sit down whenever possible when taking sublingual glyceryl trinitrate.
Pregnancy and Lactation
Use in pregnancy is not recommended unless considered essential by a physician.
Glyceryl trinitrate is primarily used for treatment and prevention of angina and therefore experience of use in pregnancy is limited. Glyceryl trinitrate should not be used during pregnancy particularly during the first trimester unless the potential benefits outweigh the unknown risks to the foetus (Briggs, 2011). Schaefer (2007) comments that nitrates may be used in pregnancy for appropriate indications and toxic affects on the foetus have not been reported. Briggs (2011) adds that with smaller doses of nitrates a transient decrease in the mother's blood pressure may occur but does not seem to be sufficient to affect placental perfusion.
The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14-17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).
Use with caution during breastfeeding. Sublingual glyceryl trinitrate has not been studied during breastfeeding.
Studies with other topical preparations (ointment) have been used to treat anal fissures on nursing mothers and there were no reported effects in the breastfed infant whilst a number of the known side effects (headache, dizziness, lightheaded) where reported in the mothers.
It is recommended that infants be observed for flushing and discomfort following breastfeeding, since it is not known if glyceryl trinitrate is secreted in the breast milk. Hale (2010) recommends monitoring for methemoglobinemia and breastfeeding with caution at increased dosages with prolonged exposure, particularly in infants younger than 6 months.
Toxic effects on the infant have not been reported; Schaefer (2007) states that data would argue against a toxic risk for the breastfed infant due to the short half-life of the drug and its usually brief use.
Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1
Tablet(s) should be placed under the tongue and allowed to dissolve slowly. A fresh tablet should produce a slight burning sensation when placed under tongue; if not obtain fresh supply.
If patient has dry mouth, prior to tablet insertion they should moisten buccal mucosa.
Allergic skin reactions
Burning sensation (local)
Decrease in blood pressure
Glaucoma (closed angle)
Increased intra-ocular pressure
Tolerance to this drug and cross tolerance to other nitrates
Worsening of angina
It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.
The following number will direct the caller to the relevant local centre (0844) 892 0111
Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).
Last Full Review Date: May 2013
British National Formulary, 65th Edition (March - September 2013) Pharmaceutical Press, London.
Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 2nd edition (2007) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.
Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 9th edition (2011) ed. Briggs, G., Freeman, R. and Yaffe, S. Lippincott Williams & Wilkins, Philadelphia.
Martindale: The Complete Drug Reference, 37th edition (2011) ed. Sweetman, S. Pharmaceutical Press, London.
Medications and Mothers' Milk, 14th Edition (2010) Hale, T. Hale Publishing, Amarillo, Texas.
Summary of Product Characteristics: Glyceryl trinitrate tablets BP 500 micrograms. Actavis UK Ltd. Revised December 2012.
Summary of Product Characteristics: Glyceryl trinitrate tablets BP 600 micrograms. Actavis UK Ltd. Revised December 2012.
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