DOXYCYCLINE- doxycycline capsule
PD-Rx Pharmaceuticals, Inc.
Rx only To reduce the development of drug-resistant bacteria and maintain the effectiveness of doxycycline capsules and other antibacterial drugs, doxycycline capsules should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.
Doxycycline is a broad-spectrum antibacterial synthetically derived from oxytetracycline. Doxycycline capsules USP, 50 mg, 75 mg, and 100 mg contain doxycycline monohydrate equivalent to 50 mg, 75 mg, and 100 mg of doxycycline for oral administration. The chemical designation of the light yellow to pale yellow powder is 2-Naphthacenecarboxamide, 4-(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-,[4 S -(4α,4aα,5a,5aα,6a,12aα)]-, monohydrate.
C 22 H 24 N 2 O 8 • H 2 O M.W. = 462.45
Doxycycline has a high degree of lipid solubility and a low affinity for calcium binding. It is highly stable in normal human serum. Doxycycline will not degrade into an epianhydro form.
Inert ingredients: colloidal silicon dioxide; magnesium stearate; microcrystalline cellulose; sodium starch glycolate; and a hard gelatin capsule which contains FD & C Red # 3, D&C Yellow # 10, titanium dioxide, gelatin, sodium lauryl sulfate for the 50 mg strength; iron oxide black, iron oxide red, iron oxide yellow, titanium dioxide, gelatin, sodium lauryl sulfate for the 75 mg strength and iron oxide black, iron oxide red, iron oxide yellow, titanium dioxide, FD & C Red # 3, D&C Yellow # 10, gelatin, sodium lauryl sulfate for the 100 mg strength. The capsules are printed with edible ink containing shellac, titanium dioxide, black iron oxide, brown iron oxide and potassium hydroxide for 50 mg, 75 mg and 100 mg strengths.
Tetracyclines are readily absorbed and are bound to plasma proteins in varying degrees. They are concentrated by the liver in the bile and excreted in the urine and feces at high concentrations in a biologically active form. Doxycycline is virtually completely absorbed after oral administration.
Following a 200 mg dose of doxycycline monohydrate, 24 normal adult volunteers averaged the following serum concentration values:
|Average Observed Values|
|Maximum Concentration||3.61 mcg/mL (± 0.9 sd)|
|Time of Maximum Concentration||2.60 hr (± 1.10 sd)|
|Elimination Rate Constant||0.049 per hr (± 0.030 sd)|
|Half-Life||16.33 hr (± 4.53 sd)|
Excretion of doxycycline by the kidney is about 40%/72 hours in individuals with normal function (creatinine clearance about 75 mL/min). This percentage excretion may fall as low as 1-5%/72 hours in individuals with severe renal insufficiency (creatinine clearance below 10 mL/min). Studies have shown no significant difference in serum half-life of doxycycline (range 18 to 22 hours) in individuals with normal and severely impaired renal function.
Hemodialysis does not alter serum half-life.
Population pharmacokinetic analysis of sparse concentration-time data of doxycycline following standard of care intravenous and oral dosing in 44 pediatric patients (2-18 years of age) showed that allometrically -scaled clearance (CL) of doxycycline in pediatric patients ≥2 to ≤8 years of age (median [range] 3.58 [2.27-10.82] L/h/70 kg, N=11) did not differ significantly from pediatric patients >8 to 18 years of age (3.27 [1.11-8.12] L/h/70 kg, N=33). For pediatric patients weighing ≤45 kg, body weight normalized doxycycline CL in those ≥2 to ≤8 years of age (median [range] 0.071 [0.041-0.202] L/kg/h, N=10) did not differ significantly from those >8 to 18 years of age (0.081 [0.035-0.126] L/kg/h, N=8). In pediatric patients weighing >45 kg, no clinically significant differences in body weight normalized doxycycline CL were observed between those ≥2 to ≤8 years (0.050 L/kg/h, N=1) and those >8 to 18 years of age (0.044 [0.014-0.121] L/kg/h, N=25). No clinically significant difference in CL between oral and IV dosing was observed in the small cohort of pediatric patients who received the oral (N=19) or IV (N=21) formulation alone.
Doxycycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit. Doxycycline has bacteriostatic activity against a broad range of Gram-positive and Gram-negative bacteria.
Cross resistance with other tetracyclines is common.
Doxycycline has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections ( see INDICATIONS AND USAGE).
Nocardiae and other Actinomyces species
Treponema pallidum subspecies pertenue
Balantidium coli Entamoeba species
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