野外活動或登山健行, 通常會建議民眾準備一些口服藥物或外用藥物備用, 因為在無法立即到達醫療院所的時候, 適度使用藥物可以緩解某些醫療狀況, 例如腸胃炎, 發燒, AMS造成頭痛, 暈車, 外傷等等.
大部分藥物可以經口服達到療效, 而極少部分狀況, 需要準備注射型藥物, 例如過敏性休克, 高海拔腦水腫, 病患神智不清無法吃藥, 病患因嚴重嘔吐無法吃藥等等.
注射型藥物基本上都需要醫師處方才能使用, 非緊急情況, 不建議民眾自行使用. 但野外或偏遠地方, 發生緊急狀況, 根本來不及送醫, 沒有幫病患適當急救處置, 可能會死於到醫院之前, 這種情況會需要用到注射型藥物
口服藥物和注射藥物差異，跟生體可用率和首渡效應有關，另外，腸胃道疾病也可能影響藥物吸收。
口服 dexamethasone 生體可用率約 81％，所以口服 8mg 與肌肉注射 6mg 的效果相似。
Obstet Gynecol. 1997 Feb;89(2):276-80.
A comparison of the bioavailability of oral and intramuscular dexamethasone in women in late pregnancy.
Egerman RS1, Pierce WF 4th, Andersen RN, Umstot ES, Carr TL, Sibai BM.
Author information
A comparison of the bioavailability of oral and intramuscular dexamethasone in women in late pregnancy.
Egerman RS1, Pierce WF 4th, Andersen RN, Umstot ES, Carr TL, Sibai BM.
Author information
Abstract
OBJECTIVE:
To compare the bioavailability of oral and intramuscular (i.m.) dexamethasone in third-trimester pregnant women.
METHODS:
Oral and i.m. dexamethasone levels were compared in a randomized, parallel, crossover bioavailability study involving 11 gravid women in the third trimester of pregnancy. Subjects were randomized to receive either 6 mg of i.m. or 8 mg of oral dexamethasone. The following week, the alternative regimen was administered. Serial blood samples were obtained after drug administration. Dexamethasone concentrations were measured by radioimmunoassay. Total area under the curve was compared for the oral and i.m. groups using a paired t test.
RESULTS:
Eight of the 11 women completed the study through 12 hours; all 11 women completed the study through 6 hours. Among the 11 women, peak levels of dexamethasone occurred 30 minutes after i.m. injection (mean +/- standard deviation, 101.7 +/- 19.2 ng/mL) and 120 minutes after oral administration (65.9 +/- 20.5 ng/mL). Area under the curve did not differ significantly between those receiving i.m. dexamethasone (258.3 +/- 50.0 ng/minute/mL) and those receiving oral dexamethasone (251.8 +/- 59.7 ng/minute/mL) when measured 6 hours after administration of the drug. Terminal half-lives were similar in the i.m. and oral groups. Similar findings were noted among the eight women who were studied through 12 hours. This study had a power of 87% to detect a 20% difference in area under the curve between the two groups.
CONCLUSION:
The bioavailability of 8 mg of oral dexamethasone is similar to that of a 6-mg IM dose, as determined by the area under the curve.
PMID: 9015035 [PubMed - indexed for MEDLINE]
OBJECTIVE:
To compare the bioavailability of oral and intramuscular (i.m.) dexamethasone in third-trimester pregnant women.
METHODS:
Oral and i.m. dexamethasone levels were compared in a randomized, parallel, crossover bioavailability study involving 11 gravid women in the third trimester of pregnancy. Subjects were randomized to receive either 6 mg of i.m. or 8 mg of oral dexamethasone. The following week, the alternative regimen was administered. Serial blood samples were obtained after drug administration. Dexamethasone concentrations were measured by radioimmunoassay. Total area under the curve was compared for the oral and i.m. groups using a paired t test.
RESULTS:
Eight of the 11 women completed the study through 12 hours; all 11 women completed the study through 6 hours. Among the 11 women, peak levels of dexamethasone occurred 30 minutes after i.m. injection (mean +/- standard deviation, 101.7 +/- 19.2 ng/mL) and 120 minutes after oral administration (65.9 +/- 20.5 ng/mL). Area under the curve did not differ significantly between those receiving i.m. dexamethasone (258.3 +/- 50.0 ng/minute/mL) and those receiving oral dexamethasone (251.8 +/- 59.7 ng/minute/mL) when measured 6 hours after administration of the drug. Terminal half-lives were similar in the i.m. and oral groups. Similar findings were noted among the eight women who were studied through 12 hours. This study had a power of 87% to detect a 20% difference in area under the curve between the two groups.
CONCLUSION:
The bioavailability of 8 mg of oral dexamethasone is similar to that of a 6-mg IM dose, as determined by the area under the curve.
PMID: 9015035 [PubMed - indexed for MEDLINE]
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