WordNet

travel or traverse (a distance); "This car does 150 miles per hour"; "We did 6 miles on our hike every day"
the syllable naming the first (tonic) note of any major scale in solmization (同)doh, ut
proceed or get along; "How is she doing in her new job?"; "How are you making out in graduate school?"; "Hes come a long way" (同)fare, make_out, come, get along
create or design, often in a certain way; "Do my room in blue"; "I did this piece in wood to express my love for the forest" (同)make
carry on or function; "We could do with a little more help around here" (同)manage
get (something) done; "I did my job" (同)perform
treat with an agent; add (an agent) to; "The ray dosed the paint"
the quantity of an active agent (substance or radiation) taken in or absorbed at any one time (同)dosage
a measured portion of medicine taken at any one time (同)dosage
the ratio of the gross weight of an airplane to some factor determining its lift
the labor of putting a load of something on or in a vehicle or ship or container etc.; "the loading took 2 hours"
treated with some kind of application; "a mustache dosed with bear grease"

PrepTutorEJDIC

《疑問文・否定文を作る》 / 《否定命令文を作る》 / 《助動詞とbe動詞のどちらも含まない文に用いて付加疑問を作る》 / 《強意語として》 / 《文》《助動詞とbe動詞のどちらも含まない文に用いて倒置文を作る》 / 《あいづちを打つ場合に》 / 《先行する動詞またはそれを含む述部の代用》 / 《so,nor,neitherで始まる簡略文で》 / …‘を'『する』,行う,果たす / 《通例have done,時にbe doneの形で》…‘を'『終える』,済ませる / …‘を'作る,作り出す / …‘を'『処理する』,整える,片付ける / 〈学課〉‘を'『勉強する』,専攻する / 〈利益・害など〉‘を'与える,もたらす / 〈人〉‘に'『役立つ』,用が足りる(serve) / …の速度で進む,距離を行く / …‘を'見物する / 〈劇〉‘を'上演する;…‘の'役を演じる / …の役目(仕事)をする / 《おもに英》…‘を'だます,かつぐ / 《話》…をへとへとにさせる / 『する』;活動する / 《通例have done,時にbe doneの形で》(…を)『終える』,済ます《+『with』+『名』》 / 〈事が〉『運ぶ』;〈人が〉暮らしていく,健康である / 〈物が〉(…に)『間に合う』,十分である;〈人が〉(…に)役に立つ,向く《+『for』+『名』》 / 《複数形で》すべきこと / 〈C〉《おもに英》大宴会,大パーティー / 〈C〉《英話》詐欺,ぺてん
ド(全音階の第1音)
(おもに飲み薬1回分の)『服用量』 / (痛いこと・いやなことの)1回分,一定量 / (人などが受ける放射線の)線量 / 性病 / (…を)…‘に'投薬する,服用させる《+『名』+『with』+『名』》

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/08/24 02:41:33」(JST)

wiki en

A loading dose is an initial higher dose of a drug that may be given at the beginning of a course of treatment before dropping down to a lower maintenance dose.^[1]

A loading dose is most useful for drugs that are eliminated from the body relatively slowly, i.e. have a long systemic half-life. Such drugs need only a low maintenance dose in order to keep the amount of the drug in the body at the appropriate therapeutic level, but this also means that, without an initial higher dose, it would take a long time for the amount of the drug in the body to reach that level.

Drugs which may be started with an initial loading dose include digoxin, teicoplanin, voriconazole and procainamide. Phenytoin for acute status epilepticus should also be given with an initial loading dose, co-administered with a benzodiazepine, to immediately stabilize neuronal membranes and electrical activity during a seizure.

Worked example[edit source | edit]

For an example, one might consider the hypothetical drug foosporin. Suppose it has a long lifetime in the body, and only ten percent of it is cleared from the blood each day by the liver and kidneys. Suppose also that the drug works best when the total amount in the body is exactly one gram. So, the maintenance dose of foosporin is 100 milligrams (100 mg) per day—just enough to offset the amount cleared.

Suppose a patient just started taking 100 mg of foosporin every day.

On the first day, they'd have 100 mg in their system; their body would clear 10 mg, leaving 90 mg.
On the second day, the patient would have 190 mg in total; their body would clear 19 mg, leaving 171 mg.
On the third day, they'd be up to 271 mg total; their body would clear 27 mg, leaving 244 mg.

As one can see, it would take many days for the total amount of drug within the body to come close to 1 gram (1000 mg) and achieve its full therapeutic effect.

For a drug such as this, a doctor might prescribe a loading dose of one gram to be taken on the first day. That immediately gets the drug's concentration in the body up to the therapeutically-useful level.

First day: 1000 mg; the body clears 100 mg, leaving 900 mg.
On the second day, the patient takes 100 mg, bringing the level back to 1000 mg; the body clears 100 mg overnight, still leaving 900 mg, and so forth.

Calculating the loading dose[edit source | edit]

Four variables are used to calculate the loading dose:

C_p	= desired peak concentration of drug
V_d	= volume of distribution of drug in body
F	= bioavailability
S	= salt fraction

The required loading dose may then be calculated as

For an intravenously administered drug, the bioavailability F will equal 1, since the drug is directly introduced to the bloodstream. If the patient requires an oral dose, bioavailability will be less than 1 (depending upon absorption, first pass metabolism etc.), requiring a larger loading dose.

Sample values and equations[edit source | edit]

Characteristic	Description	Example value	Formula
Dose	Amount of drug administered.	500 mg	Design parameter
Dosing interval	Time between drug dose administrations.	24 h	Design parameter
C_max	The peak plasma concentration of a drug after administration.	60.9 mg/L	Direct measurement
t_max	Time to reach C_max.	3.9 h	Direct measurement
C_min	The lowest (trough) concentration that a drug reaches before the next dose is administered.	27.7 mg/L	Direct measurement
Volume of distribution	The apparent volume in which a drug is distributed (i.e., the parameter relating drug concentration to drug amount in the body).	6.0 L
Concentration	Amount of drug in a given volume of plasma.	83.3 mg/L
Elimination half-life	The time required for the concentration of the drug to reach half of its original value.	12 h
Elimination rate constant	The rate at which a drug is removed from the body.	0.0578 h⁻¹
Infusion rate	Rate of infusion required to balance elimination.	50 mg/h
Area under the curve	The integral of the concentration-time curve (after a single dose or in steady state).	1,320 mg/L·h
Area under the curve		1,320 mg/L·h
Clearance	The volume of plasma cleared of the drug per unit time.	0.38 L/h
Bioavailability	The systemically available fraction of a drug.	0.8
Fluctuation	Peak trough fluctuation within one dosing interval at steady state	41.8 %	where
[ v t e ]

References[edit source | edit]

^ "Cp vs time - iv infusion with loading dose".

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Japanese Journal

教授就任記念講演がん放射線療法 : 技術革新がもたらす真の治療適応

生島仁史
四国医学雑誌 = Shikoku acta medica 68(3・4), 97-110, 2012-08-25
… Technical innovation in radiation therapy symbolized by stereotactic irradiation, intensitymodulatedradiation therapy, image-guided radiation therapy, and brachytherapy using remotecontrolled after-loading system made it possible to deliver ideally distributed radiation dose to thetarget with great accuracy, while sparing the adjacent organs at risk. …
NAID 40019424295

Predictors of High On-Treatment Platelet Reactivity Early After Clopidogrel Loading in ST-Elevation Myocardial Infarction

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… Methods and Results: Consecutive STEMI patients admitted for PPCI were considered for platelet reactivity assessment 2h after loading with 600mg clopidogrel using the VerifyNow point-of-care P2Y12 assay. … Patients with high on-treatment platelet reactivity had received upstream clopidogrel loading and pantoprazol more frequently, had lower admission hemoglobin and tended to have an impaired renal function compared to those with an adequate response to clopidogrel. …
NAID 10030696736