Considerations for IV-to-PO Conversions

Acetazolamide

Doses for IV and immediate-release tabs are the same.³

NA

Amiodarone

If <1 week IV infusion: switch to 400 to 1,600 mg/day PO.¹⁴

If 1 to 2 weeks IV: switch to 400 to 800 mg/day PO.¹⁴

If >2 weeks IV: switch to 100 mg to 400 mg/day PO.¹⁴

Administer above oral doses until total load (IV plus PO) of 6 g to 10 g is reached, then start oral maintenance dose (100 mg to 400 mg once daily, depending on the indication).¹⁴

Oral dosing is dependent on the indication.¹⁴

Oral doses can be given once daily or divided BID if patients have GI intolerance or total daily dose is
800 mg to 1,000 mg or higher.

Ampicillin

Convert to PO amoxicillin.⁶ Dose conversion will depend on indication. Ampicillin and amoxicillin have nearly identical spectrums of activity.⁴ 

Amoxicillin has better GI absorption than PO ampicillin.⁴

Ampicillin-sulbactam

Convert to PO amoxicillin-clavulanic acid. Dose conversion will depend on indication. Ampicillin-sulbactam and amoxicillin–clavulanic acid have nearly identical spectrums of activity.⁴

NA

Azithromycin

500 mg IV Q24H to 500 mg PO Q24H.⁶

NA

Bumetanide

Dose of IV and PO bumetanide are the same.³

Up to 85% to 95% of oral bumetanide is absorbed.³

Cefazolin

Convert cefazolin 1 g IV Q8H to cephalexin 500 mg PO Q6H.⁶

NA

Ciprofloxacin

200 mg IV Q12H to 250 mg PO Q12H.³

400 mg IV Q12H to 500 mg PO Q12H.³

400 mg IV Q8H to 750 mg PO Q12H.³

NA

Clindamycin

Convert 600 mg IV Q8H to 300 to 450 mg PO Q6H.⁶

NA

Dexamethasone

Doses of IV and PO dexamethasone are the same.⁷

The bioavailability of oral dexamethasone has been reported as 60% to 100%.³

Digoxin

50 mcg IV to 62.5 mcg (0.0625 mg) PO.

100 mcg IV to 125 mcg (0.125 mg) PO.

200 mcg IV to 250 mcg (0.25 mg) PO.

400 mcg IV to 500 mcg (0.5 mg) PO.

Digoxin oral tablets are 60% to 80% bioavailable.

Diltiazem

For an IV infusion rate of:

Convert to PO dose of:¹⁰

Oral dose =
(IV drip rate [mg/hr] x 3 + 3) x 10.¹⁰

Divide daily doses of oral products as appropriate per formulation.

3 mg/hr

120 mg/day

5 mg/hr

180 mg/day

7.5 mg/hr

260 mg/day

10 mg/hr

330 mg/day

15 mg/hr

480 mg/day

Doxycycline

Dose and frequency of IV and immediate-release PO are the same.⁵

NA

Enalaprilat

For Hypertension:

Enalaprilat 1.25 mg IV Q6H to enalapril 5 mg/day PO.

Enalaprilat 0.625 mg IV Q6H to enalapril 2.5 mg/day PO.

Adjust initial dose based on blood pressure response.

Oral enalapril doses may be given once daily or divided twice daily.³

Esomeprazole

Dose and frequency of IV and PO esomeprazole are similar.⁵

Bioavailability of oral esomeprazole is around 90% with repeated daily dosing.³

Famotidine

Dose and frequency of IV and PO famotidine are the same.⁵

NA

Fluconazole

Doses of IV and PO fluconazole are the same.⁶

NA

Furosemide

IV to PO conversion is ~1 mg IV to 2 mg PO.¹²

Bioavailability is ~50% for furosemide tablets and oral solution.¹²

Hydrocortisone

Doses of IV and PO hydrocortisone are the same.⁷

Corticosteroid dose and dose frequency is determined by disease severity.

Hydromorphone

1.5 mg IV is equianalgesic to 6 to 7.5 mg of immediate-release PO.^8,13

Dose conversions are approximate. Titrate to response.

See our chart, Equianalgesic Dosing of Opioids for Pain Management, for more details.

Hydralazine

Double the IV dose and administer orally, then titrate to effect.³

NA

Isavuconazonium

Doses and frequency of IV and PO isavuconazonium are the same.³

NA

Labetalol

Following inpatient IV treatment, start PO treatment with 200 mg PO x1, then 200 or 400 mg PO 6 to 12 hours later depending on blood pressure response.

Titrate PO dose up to 1,200 mg Q12H if needed.

Administer an oral dose once blood pressure has started to increase following discontinuation of IV labetalol.

Lacosamide

Dose and frequency of IV and PO lacosamide are the same.³

NA

Levetiracetam

Dose and frequency of IV and PO (immediate-release) are the same.⁵

NA

Levofloxacin

Dose and frequency of IV and PO are the same.⁶

NA

Levothyroxine

Increase the IV dose by ~20% to 25% for oral administration. Dose should then be titrated based on clinical status and lab results.³

Bioavailability of oral levothyroxine is about 50% to 75%.³

Linezolid

600 mg IV Q12H to 600 mg PO BID.⁶

NA

Methylprednisolone

Dose of IV and PO methylprednisolone are the same.^3,7

Methylprednisolone 4 mg is equivalent to prednisone or prednisolone
5 mg.^3,7

Corticosteroid dose and dose frequency is determined by disease severity.

Metoprolol

Equivalent maximal beta-blocking effect may be achieved with IV and PO doses (mg) in a ratio of 1:2.5.

Note that patient variability may exist and caution should be used if converting patients on large chronic oral doses to intravenous metoprolol. For example, consider converting an oral daily dose of 50 mg to 2.5 mg to 5 mg IV Q6H (ratio range of 5:1 to 2.5:1).¹⁴

The duration of action is shorter with the IV formulation, compared to oral. Monitor and adjust dose as needed.⁹

Divide daily doses of oral products as appropriate per formulation.

Metronidazole

Doses of IV and PO are the same.⁶

NA

Morphine

10 mg IV is equianalgesic to 30 mg PO.^8,13

Dose conversions are approximate. Titrate to response.

See our chart, Equianalgesic Dosing of Opioids for Pain Management, for more details.

Moxifloxacin

400 mg IV Q24H to 400 mg PO Q24H.⁵

NA

Pantoprazole

Dose and frequency of IV and PO pantoprazole are the same.⁵

NA

Phenytoin

The total daily dose of IV and PO phenytoin are the same.⁵ 

Note that frequency differs. IV is often administered Q8H while oral forms should be administered based on the formulation (which may be once daily if extended-release).

Bioavailability of oral phenytoin is 90% to 100%; however, absorption rates vary between different products.³

Rifampin

Dosing recommendations for IV and PO rifampin are the same.⁵

NA

Trimethoprim-sulfamethoxazole

Dose and frequency of IV and PO are the same.⁶

NA

Valproate sodium

The total daily dose of IV valproate sodium and oral valproic acid/divalproex products are the same.³

Divide daily doses of oral products as appropriate per formulation.

Voriconazole

Convert 200 mg IV Q12H to 200 mg PO Q12H.^5,6

NA