Chemical stability of sublingual nitroglycerin tablets carried on paramedic vehicles

Environmental temperature variations cause degradations in epinephrine concentration and biological activity

This study determined the biological consequence of temperature induced epinephrine degradation. Two different epinephrine preparations (1:1,000 and 1:10,000) were exposed to either cold (5 degrees C) or hot (70 degrees C) temperature. The exposure occurred for 8-hour periods each day in 4-, 8-, and 12-week intervals. Samples and identical controls were then chemically evaluated using high-pressure liquid chromatography (HPLC), and biological activity of samples showing chemical degradation was assessed in conscious rats. Epinephrine (1:10,000) underwent a significant degradation and a loss of concentration of the parent compound after 8 weeks of heat treatment. By 12 weeks, 64% of the epinephrine was degraded. A smaller (30%) but significant loss of cardiovascular potency was determined by blood pressure and heart rate responses in conscious rats. The degradation of epinephrine (1:1,000) was not statistically significant even after 12 weeks of heat exposure. No change was noted from control in either epinephrine concentration when exposed to cold temperatures. In conclusion, epinephrine (1:10,000) deteriorates in the presence of elevated temperature and should be protected from high temperatures when carried by EMS providers. The degradation products may possess biological activity.

The prehospital use of nitroglycerin according to standing medical orders in an urban EMS system

PURPOSE

The purposes of this study are to quantify the use of nitroglycerin (NTG) in prehospital care, to detect deviations from the Standing Medical Orders (SMO), to determine the effectiveness of its administration, and the incidence of clinically significant adverse reactions (hypotension, bradycardia).

METHOD

Retrospective review of 7683 Advanced Life Support (ALS) telemetry, base-station contacts over a three month period (June, July, August 1990) to identify all prehospital patient contacts in which NTG was utilized.

SETTING

The Resource Hospital/Telemetry Base-Station and two community hospitals/Telemetry Base-Stations for the Chicago North EMS System.

RESULTS

There were 445 runs in which NTG was indicated as per SMO. Two hundred eighty-eight patients (64.7%) received NTG for appropriate indications as per SMO, 203 for ischemic chest pain (45.6%), 79 for pulmonary edema (17.7%), and six for both (1.3%). There were 157 (35.5%) runs in which NTG was indicated, but not administered. There were 22 patients who received NTG for indications that deviated from the SMO. Reassessment data concerning the subjective symptom was completed on 118 patients (40.9%), 92 (45.3%) patients with chest pain and 26 with dyspnea (32.9%). Following the administration of NTG, 21 patients (10.1%) with chest pain were unchanged, while 13 with dyspnea (15.3%) improved, 13 patients (15.3%) were unchanged, and none worsened. In 121 patients, the systolic blood pressure (SBP) decreased, while 24 were unchanged (5.4%), and 28 had an increase (6.3%). The mean initial value SBP was 176 +/- 44 mmHg and the repeat mean SBP was 164 +/- 41 mmHg with a mean decrease of 12 +/- 22 mmHg. The diastolic blood pressure (DBP) decreased in 87 patients, was unchanged in 53 (11.9%), and increased in 33 (7.4%). The initial mean DBP was 97 +/- 24 mmHg, the repeat mean DBP was 92 +/- 23 mmHg, a mean decrease of 5 +/- 15 mmHg. Only one patient became hypotensive with the administration of NTG and was successfully resuscitated with a fluid bolus of 300 ml normal saline.

CONCLUSIONS

In this EMS system, NTG is under-utilized based on the indications delineated by this system's SMOs. Reassessment is documented infrequently, but when completed, clinically significant adverse reactions are rare. Since the incidence of hypotension and bradycardia are rare, the inability to establish an IV line should not preclude the administration of NTG.

Nitroglycerine Lingual Aerosol in Prehospital Emergency Care,

Nitroglycerine (NTG) commonly is used in the prehospital emergency care setting for the treatment of chest pain suggestive of myocardial ischemia or infarction or for cardiac unloading in patients with presumed pulmonary edema. The usual form of this drug is as a 400 mcg tablet administered sublingually. Recently, NTG has become available as an aerosolized form (NTGA) in a multiple dose, pressurized canister containing 200 metered doses of 400 meg of NTG each. In this form, the drug is purported to be absorbed rapidly from the surface of the tongue.

In the field, we have noted that the sublingual tablet form of NTG occasionally remains undissolved following administration to patients complaining of chest pain. In each of these cases, clinically, the patients were unchanged on arrival at the receiving hospital and an intact tablet was discovered properly placed under the tongue. In an attempt to evaluate the ease of administration and clinical responses of patients with chest pain to the aerosolized form of the drug, we replaced NTG sublingual tablets on paramedic units in the Burbank system with the NTGA form.